The game was actually very loose passive (something like 38/5), and A7s is much better than A2s.

I think you're being too restrictive with the A outs. I don't see any use in discounting all of them, unless we are specifically against AA, which is unlikely. We have 2 outs to reverse dominate another A. Maybe you're assuming that every A is out there? I think 2 outs is the minimum for the A, making at least 5 outs total. I think it would be extremely incorrect to fold this flop ever.