PyPA member here - if this PR is defining new compatibility tags, I would have expected it to need discussion as a revision to PEP 425, much like the manylinux efforts did. (It may actually be a closer parallel with MacOS, which didn't have a tagging PEP - I'm not sure how that would relate here, but as MacOS is a much more mainstream platform I'd be inclined to err on the side of caution and look for AIX to be explicitly covered in the tag specs).

I thought that was something that had been discussed on the Pip tracker, but maybe the implications weren't clear (I don't really understand the AIX scheme, so I'm relying on someone else, probably Michael, to propose something that could be added to PEP 425 and to lead/guide the discussion).