Question about Cheat! After thief steal

[Fzh]

Hi everyone, I hope you guys can give me some clarity on this issue.

So my friend is a thief and he successfully stole an item on my playing field that's only usable by cleric. While he isn't a cleric, he played a cheat! Card on it after steaing it and claimed that he can now use it.

I argued that the cleric condition is checked first right after he steals it. Therefore, he must immediately discard the stolen item right away. Since the cheat card says "play with an item you have in play or a card from your hand." And HE could never have had the item in play since the cleric condition is checked and returned false.

What is the jurisdiction on this?