"OL, protect yourselves. Defense, if the QB takes a knee, I better not see anything unsportsmanlike." Done - that's it. No other advice or restrictions on anyone.
Now.... let's say you're in the other camp, and you are going to tell the defense to take it easy - you HAVE to warn the offense that if they don't take a knee you are going to call USC (on the coach, of course).
I vastly prefer the first method, because if offense drops the snap, and you've told defense not to play, you've possibly deprived them of a chance to win the game. Speaking of unfair acts!
PS - offense up by 10, seconds to go, going for a TD? Are you SURE there wasn't holding on that play?
(not serious)