I'll put this a calmly as I can (unless you would want me to Rant, You should see me rant on discord, don't worry I have a special room for it

)
Anyway, locking a tileset behind a kind of "paywall" is never a good thing.
Especially if someone doesn't have the time to solve puzzles of your level or can't because they feel stumpted and they can't do anything about it.
Now if it were temporary paywall, I would cut it some slack, I know you mean well as a prize but I heard how tough your puzzles are, and experienced them first hand I don't think putting behind a paywall that could be the hardest level pack which could rival "Nepsterlems"
Some people (Myself included) are dying to edit with your minimal tileset, and IMO All Tilesets that are remotely finished should be released to public after sometime has passed.
Plus, I don't want to do something as shady as bother someone else to give it to me but never share it anywhere else after that.