[Hawks Coach]

First, everyone in the gym is capable of seeing the foot on the line, but in reality, nobody in the gym is looking at the player on the 3 point line if they haven't been going after rebounds. Also, everybody in the gym is theoretically capable of knowing and understanding the rule on this play, but few actually do.

So what you have is something that you see that is a minor technical violation of a rule with no impact on the play. The rule exists for a purpose, to prevent an unfair advantage. But if the player stays out of the play, then they haven't gained an advantage. If the player is pushing their limits to e the first one to a long rebound, they have gained an advantage.

Here is where the judgement in this call really lies. Judge whether or not this "violation" impacted the play in any way, and therefore if this is a call you really need to make. Call what matters, not every technical rules violation you can see. You are not the local health department inspector, you are refereeing a basketball game. Don't make it harder, or more nit-picky, than it has to be.

Now when you add "the opposing coach saw it" into the description of the situation, it makes it a bit tougher. I am not a big advocate of telling coaches that you pass on certain things (especially if he is already a whiner/howler). Good coaches know this anyway and aren't looking for that call. They are also paying attention to what matters in the game. So telling an uninformed coach that it is your job to exercise judgment in what to call can get dicey - you decide if that is where you want to be. It is a simple enough thing to use another out so you don't have to go down that path - "thanks Coach, I'll look for it next time" is one I have heard used frequently - shut em up without being completely non-responsive or combative.