Two reaction to this discussion:

1. I would have no reservation about doing what the OP had proposed. I'm pretty sure I've done something similar. MSY is home for me now, but I often originate my international travel from other airports because I often can save a lot of money (particularly when flying J or F). I'm sure there have been instances where I couldn't check in for my international flights so just flew from MSY to my gateway and checked in there at the gate or at the lounge. Never an issue.

2. Are we still doing VeriFly? I travel internationally frequently (I'm in Copenhagen right now) and don't remember the last time I used the VeriFly app. There have been instances where I tried to check in online and was told I had to do it at the airport, but typically I'm able to go back to my record and find some information missing -- almost always a scan of my passport -- and this always resolves the situation and lets me check in online. On my current trip, I'm traveling BA, but the exact same thing happened on the BA app. Initially it told me that I had to check in at the airport, but when I went back and re-entered all of my passport info (which I guess hadn't transferred from AA, through which I booked the flights) it all worked perfectly.