I don't blame anybody for Punk's "spot" - as has been said, props to Punk for even getting in the Octagon - akin to Jordan or Tebow trying baseball after their first careers were done, but UFC saw a marketing opportunity and they will make money off this card because of Punk's wrestling popularity. It's simply smart business on their part.
I agree more with Fatty that UFC is giving Punk the most credible opponent they can while giving Punk a chance to gain a victory. Yes, Gall only has two pro fights, but most likely got his UFC contract primarily because he was 3-0 with two submission stoppages as an amateur, and held titles in other organizations (all of which no one has really heard of, but it adds to the resume).