Collisions between runners trying to score and catchers wanting to tag the runner out have always been and always will be part of baseball. It's unfortunate that an injury sometimes results to either player, but that's baseball. I don't see the value of, and would not enforce, rules that protect players from what has always been a normal risk of the game. If it were my play and the catcher dropped the ball and the runner touched the plate, he's safe and the run scores. Now, if afterwards, there's a fight as a result of the play (as often happens in these situations) there would probably be some ejections depending on who was the aggressor, who left their position or the dugout to get involved, etc. If the manager came out to complain about his catcher getting knocked down, I would probably ask the manager what kind of sissy he's got behind the plate, which would probably get the manager angry enough to do something warranting an ejection.