"Wait 12 months" - is a standard stalling tactic. 12 months is when his obligation to you runs out. (What a coincidence!) People have revisions within months after surgery.
Correct. A lot of times they just tell you it's okay to make sure the statute of limitations passes. It's possible it is okay, but the photos didn't show that. I'd go get second opinions from people completely unrelated to this guy. Maybe different city, etc. Don't tell them who did the surgery. Just say you're concerned and want an objective opinion.
Agree 5k is nothing for him, but by issuing a refund he might under law be admitting culpability. And he might not want that on his record or reputation. For that reason he might fight it.
If you get a bunch of opinions, they all say something is wrong, etc, get that in writing and show him. See what he says and then go from there.
This isn't legal advice, etc etc -- just my opinion and what I'd do.