Surely, in the areas of the world where the A-10 would presently be of most use, the 'baddies' don't have any fast pointy jets, so what's the problem?
1) They could show how useful they are in that sort of situation. Thats bad for all sorts of reasons
2) I think ISIL have access to the sorts of weapons that may have a chance of bringing them down in the way they operate. Thats bad for all sorts of reasons. We would be extremely adverse to an captured pilot having their head hacked off on youtube.