I think it's the coinflip pocket pairs that people would fold this because of...

Knowing that the opponent doesn't push AA and KK makes it a lot easier to call, though I think it'd still be correct even if the opponent might have AA or KK.

There was a locked thread earlier tonight where a player complained about a SB/BB call with AJo (which was a bad call)... but the poster said only a donkey would call there without AA or KK... I've seen similar things posted here before (by good posters), which encouraged me to post this hand.