You protested a rec game? In 8u?
By ASA rule, the umpire was mistaken, however, when all is said and done, a 'strike' is anything that the umpire says it is and it's my opinion that it's never too early for softball players - and coaches/parents - to learn this. As Marriard noted, though, it's common for umpires to expand the strike zone when a batter bails out, so I'm never surprised at a strike call when they do.
Sorry to say, but he had me fired up with the "automatic strike" thing at an 8u rec game. The protest means nothing in this situation, we aren't going to replay the game or anything, just a method to point out something to the other league. As I noted previously, had he said it entered the strike zone, no argument from me, let's keep the game going. However, he made it a point to say that the reason he was calling it a strike was because she stepped out. That tells me he's taking the lazy way out and not trying to call the game the way it should be.