I guess that's open for interpretation.
Rule 9-9-1: ...A player or non-player or person(s) not subject to the rules shall not hinder play with an unfair act which has no specific rules coverage.
Is the fan causing such a racket that he hinders play? I wasn't there so I don't know, but you can see this is a broad rule because of how vague it is.
The penalty for any such act is: "the referee enforces any penalty he/she considere equitable, including the award of a score,"
So that last part should tell you what the rules writers were worried about: that someone off the field would rush out and tackle a runner, or throw something that strikes a player... something that actually, physically impacts the game. A player breaks away for a score and there's no hope to catch him, then the mascot, a cowboy on a horse wielding a lasso, ropes him and he falls. (Ridiculous, sure, but it could happen.)
My interpretation is that, no, you don't flag a fan. It's been my experience that the worse the fan behaves, the more the players on the team he supposedly supports wishes he would shut up and go away. If most of the fans knew what the players on the field were saying they'd be shocked. The white hat in the game you mentioned might have asked for some help and got none, so he decided to let the fan cost the team and then, maybe, someone on the team would do something about him. My interpretation of 9-9-1 doesn't support that, but his must.
I've got so many stories about incidents like I described, where the things being said on the field were so vastly different that what the loudmouth fans thought, they'd be stunned. I should write a book.