When I read the OP, I was going to respond as others have- with the AA rules from the OW page. But, as I read it, I saw that these didn't necessarily apply. I agree that the OP has, indeed, found an apparent loophole. Does PLT/EXP get access to a general QP/BA, whatever lounge flying AA domestically (as the rules imply)? If so, the AC/QP lounge in T4 should work. I don't know the answer to the first part, and that will play into the second part.

I also agree that, loophole aside, it won't work in practice...but someone who is not an AC member should try

Cheers.