You're trying to figure out what the payoff is in believing A-Theory, if it's not being used to solve some conceptual tizzy over free will, or are you trying to figure out how they manage not to have a tizzy over the implications of B-Theory for free will?

The first option. The second issue isn't so mysterious to me, because the usual compatibilist arguments seem to be just as available to the A-theorist as to the B-theorist. (... and just as necessary, since there are still compelling physical arguments for determinism even if you're an A-theorist.)