The point is that being passive about it encourages this type of behavior from FAs. They know that you will complain to UA, and they know that UA will do nothing about it.

The bully bullies because the bully thinks that you are too scared to do anything about it. If you actually are too scared to do anything about it, then the bully is right.

Just some stupid form letter with an apology. I'm sure the FA didn't even get a reprimand and he'll continue on his merry power-tripping way. And like the OP, I will always regret the fact I didn't call him out for it.

Very much in the realm of possibility. Default is to back the other employee even if every ounce of common sense suggests otherwise.

Even better. I would love to see how this would play out on social media once the videos are released.

This is something I ran into on a previous previous flight. Full B737, I checked a bag and brought aboard a small backpack which I put in the overhead since it was my only carryon. FA came over and asked if I could put it under the seat in front to fit somebody else's rollaboard. I paid for an extra legroom seat and it basically defeated that perk since now the backpack took up all the space under the seat in front of me.
Postflight I complained to the airline (Jetblue) and they refunded the extra legroom seat charge. I wasn't expecting anything out of the complaint, so it was pleasantly surprising they did that.

"The overhead bins are for large carry-ons only" does not make sense. Suppose I bring two personal-size items. Each of them fits under the seat, but they do not fit under the seat together. This is definitely in-policy, I can declare one of them to be a carry-on, as the carry-on rules restrict only the maximum bad size.
The policy should be that overhead bins are for carry-ons only, and pax decide which of the qualifying items is a carry-on. As a cutesy to others, I may decide to put my only carry-on item under the seat, but this is for me to decide.

I would just say no, sorry, but I didn't bring a personal item. That's my carry-on and I'd like to leave it in the overhead bin so I can be comfortable.

It's just plain foolishness to pick a fight with an FA, just as it's foolishness to mouth off to TSA or CBP. Especially AFTER the issue has already been resolved in your favor.

It's easy to talk big on line. We get this foolish bravado every time one of these threads crops up.

You are intentionally misrepresenting the situation. The fact that another passenger also brought a personal item has no effect upon the overheads unless they try to put it up there, which we've all agreed is verboten for non-bulkhead passengers.

Use of volume is misleading due to the bin packing problem. In many situations, you can replace a full-size carry on with a personal item in the bin and not free up any effective space (except, maybe space for some other person's personal time).

If everyone else has boarded, and there's room in the overhead, and you want to put your bag up, I don't have an issue with it. But I absolutely cannot fathom how you could look someone in the eye as they walk past you, having surrounded their bag to check, when you could have made room for them in the overhead and chose not to do so.

I don't see any point in continuing this conversation. This is precisely why I tried to sidestep it this weekend. I don't think I'm going to convince you, and you're absolutely not going to convince me.

It depends upon what you did next, but, yes, I do. If you had responded again, escalating the situation further, the captain would have seen a passenger making a scene and arguing with a flight attendant. And, thanks to our national paranoia over security, I think there's a realistic chance you would have ended up in handcuffs.

Nonsense. That seat was further away from you than it otherwise would have been.

I struggle with the laptop going up top or underfoot. I'm always afraid some idiot passenger will fling his 80-pound kitchen sink carry-on right on top of my laptop and crush it. I usually try and wait until boarding is completed and then find a place for it up top, otherwise leave it under the seat.

I have had discussions (not confrontations) with FAs on many occasions when I put a backup (sans laptop) up in the bin. They have largely been reasonable when I tell them I only have the backpack so I can put it up and have the legroom. I guess I have been lucky. I applaud those who stand up to bully FAs about this.

You definitely have all the rights to speak up. It just may not end up well for you or it might. There will not be another Dao situation - they have new procedures for that but don't kid yourself that it means you don't get the boot and don't risk arrest.

At a hub, the following happens, as I've now seen it 3 times - hubs are, in my opinion, the biggest risk of speaking up. They aren't as forgiving as a Captain. A guy in a suit confers with the crew on what happened. I'm guessing it is his full time job (it has all been men). The conversations all went the same - if you are in the aisle seat, they will talk to you right there - middle or window - they will politely ask the seatmates to excuse themselves. After an introduction - the guy in the suit goes - "Are we going to have a problem today". One time the passenger said, No - I'm fine - conversation ended. The other two, they try very hard to tell their side of the story - and they all get cut off with another, "Are we going to have a problem today". They had no desire to hear the other side of the story. None. One fought hard until the suit person said, "If we are going to have a problem today, we are going to make alternative arrangements - so, last time I'm asking - are we going to have a problem today" Person backed down. I can imagine at a hub, what goes in a persons profile isn't flattering.

Non-Hub - you probably have a better chance depending on training of the Captain.

Either way - if they want you off, it isn't a filmed Dao situation dragging you off with cell phones blazing. They will deplane everyone and cancel if necessary.

Well then, so be it. If enough folks who have been made a victim do this, maybe there will be a change. If we all keep putting up with this, nothing will change. And that is what is upsetting to me - that I caved in like a coward.

You didn't cave. You won.