I'm sorry but I will NEVER think that it is OK to coach between points in a match, regardless of the level. I agree that it would be fine on change overs. If you are trying to convince me, it isn't going to happen.
I'm not trying to convince you, I'm just trying to understand your reasoning. Your logic of "if it doesn't happen in the pros it shouldn't happen at college tennis" doesn't fly for me since it does happen in team events even at the pro level, and between points too.