QF SG status is also comp QP membership. So if the OP is QF SG then they get AC access because of QP membership (unless I am mistaken).
As you rightly say QF PS gets you nothing, but when SG kicks in, then you get the wonderful experience of the AC. AA is mean and doesn't let you in their domestic ACs unless you have AC membership or are visiting as part of an immediate international connection. Class of travel is irrelevant. Much like QF a year or two ago.
Wow, I guess thats my fault, should never assume anything. However it does seem harsh to have an A boarding pass and be given no access.. oh well, I'll just make sure I hit SG before I get there!