For me personally, if a player asks if you're putting them through, I say yes and they usually go fair enough.
If they try to coerce or intimidate you into not putting them through, then you should put a report in.
If they're just asking, I usually just leave it as that as they're not actually asking me to not put it in, they're just asking if you are or aren't.
In my eyes, it's a bit of a far cry to penalise them for just asking a question if they're not arguing with your decision.
Edit: forgot to add, in your case it looks like he has tried to intimidate you into dropping the caution by saying he's going to mark you down. In that case, I'd happily agree that he can mark me down however he sees fit, and would also ask him his name to put in a report about his actions.