I don't think it's a surprise, to AA or BA or any international airline, that fares vary based on point of origin. Fares are set carefully, with an eye to market conditions and competition and customer willingness to pay.

Personally I have not been harmed by this practice. When I have needed to buy RTW tickets, originating outside the US, I have been able to do so. (But of course that was some years ago, and by all indications the current problem is a new development.) If AA tried the tactic on me that is discussed in this thread, I would file the complaint contemplated here. That doesn't mean anyone else has to or wants to.