They might have taken his licence away, but how would they stop him flying?
It probably would if he was based at an airfield, because the word would get around (GA gossip travels a lot faster than a C150) that he hasn't got a PPL.
If he was based on a strip then no, but I wonder how many private strips would have somebody like that among them. From what I have seen, most are socially very tight groups which are hard to get into. I think he'd find it easier to get into a gliding club (where most members are married to each other) than into an average private strip scene
He would have to own the private site; then it would work.
Same thing really as driving with no driving license, with no roadtax, and avoiding being out near the pub closing time, and not parking on public roads
It's quite possible if nobody knows you, so when the local rag prints the court case report nobody recognises it.