Live $1/$2 hand vs short stack

[KSOT]

I had only been at the table for an orbit or two so I didn't really know how people were playing, but this guy looked like a typical passive, straight forward player. Looks were all I had to go on.

I get 55 in EP and limp, someone else limps, villain completes his SB and BB checks. Flop comes out 567r and Villain open pushes for $55. I assume he's got A7, 2 pair or some sort of pair-straight draw combo, so I obviously call. Guy flips up 48o and I don't fill up. Does ANYONE fold this to an unknown based on his appearance or other factors, or was this unavoidable?