rule 9 section 9 art. 1...a player or nonplayer or person not subject to the rules shall not hinder play by an unfair act which has no specific rule coverage.
penalty: the referee enforces any penalty he considers equitable
that could cover it but no official worth his salt would ever call anything like that, in other words, like the song says, " and the band played on...."
the most extreme case would be that an official would say something to the head coach to have him put an end to it, and if he didn't or couldn't or was being a butt about it , the ref would probably hit him with an unsportsmanlike 15 yarder . now you have a lot of attention being paid to off the field happenings instead of what's happening on the field.