The way I understand it, foreign pilots who fly into this country need to meet certain standards. They may not be exactly the same as the US standard for US pilots, but there are requirements. Their certificates need to be recognized by US authorities. The same rules apply in a reciprocal way to US pilots flying in other countries.
I understand ALPA's argument. But what's good for ALPA isn't necessarily good for the consumer. It's like the people who wish for the days before deregulation. Yes, the flying experience was better and pilots got paid more in relative terms (I think, I'm not sure about that), but it was also much more expensive.