Fellow ref riding crew as spectator

[Hawkeyes]

I'd talk to him, the school AD and your association person responsible for member conduct.
If this parent/official did this to you, he's doing it or will do it to another official; and the AD needs to have a heads up for the next time... and make him sit in the stands.
When you see the parent/official: "What did you think of my game the other night? Any feedback?" Then ask him, can I give you some feedback?: Don't stand near the court and chirp at the officials. I'm sure the association expects more from a veteran official like yourself and I won't allow you to do that during my games in the future.
Then do your millennial thing: drop the mic!