Though I haven't been flying AA a ton, I seem to have been noticing a lot more "Reserved for Flagship Business" or such (the weird language sticks out to me because these are 2-class domestic flights) stickers in overheads in F. Did this aircraft have those? Is anyone generally aware of the logic / scheme behind rolling them out?
Berating or verbally abusing an employee is never justified, but that being said...
1) I'm strongly in the camp that if you're in F, you're there for a reason - either buying the ticket or earning the upgrade through loyalty - and you need to be able to depend on what comes with it, including the ability to stow luggage.
2) If the FA's response did in fact presuppose that 1C was not an F pax, as the language the OP quoted indicates, then that could certainly be taken as an insult - especially if he was a very loyal customer or paid many $$$ for the ticket.
3) The guy could have been late due to a delayed inbound or worse - given the way AA ops have been lately, who knows what he had been through before getting to your plane!!!
Again, the guy should have kept his calm, but this isn't the ideal service experience.