I'm a middle aged white guy, so I cannot presume to know what discrimination feels like. But I know it happens to people who aren't in my shoes all the time, and I can understand how people could assume that bad treatment from AC could amount to discrimination. Maybe in these cases it was, I wasn't there and we'll probably never really know.
But given the number of issues reported on this forum that happen with AC, even to us middle aged white guys, I'm more inclined to apply Occam's razor. For example, two weeks ago connecting home in YYZ I was going for an earlier flight, but I was going to need to run to make it. Concierge had already put me on the waiting list. I sprint up to the gate sweating and ask the agent if she's cleared standby and she gives me this annoyed look and says, and I quote "the flight is full, go away". There is already a bunch of people standing around the gate waiting to try and get on the plane as well. I decide to wait around to see what happens while she resolves an issue with a lady with a GTE boarding pass ... then I guess there is one seat left on the plane and guess who is
#1 on the list. She calls my name and she wordlessly hands me my BP and points to the other agent as if to tell me to board. I know that is just a gate agent having a bad day, and not the norm, because I fly a lot ... but it isn't exactly uncommon either. As a middle aged white SE I can't explain the rude behaviour as anything else than an agent being rude. But I could sure see how someone not in my shoes would assume the agent held another bias.
TLDR;
24left is right - AC has a bigger problem here. Even if their agents deal with things well 99% of the time you are talking about thousands of crappy interactions a day which if not handled well end up in articles like this. Whether the employees in this situation discriminated against these people, or were just plain being rude.