I would also treat this like it is a good frame, because it is.

Something you could try, as long as you take your time, is pull the seat binder bolt out, thread it in from the left side and slip a penny or dime in the slot so the bolt pushes on it as the bolt is tightened. It shouldn't take a lot of this to push the ears apart until the proper 27.2 greased post will fit. If it does, you can decide to deal with it like that, or take it somewhere competent to get fixed. If it doesn't, definitely take it to somewhere competent like Bilenky.

When this kind of thing happens, it doesn't generally make the diameter smaller - it just pinches the opening into a teardrop shape. So whoever fixes it is primarily bending those two ears back out to where they belong.