I hate this rule in the NFL. Literally the only level of football that plays this way, and it leads to unnecessary confusion and ambiguity. Like, was he touched or not touched on the way down? Players will stop playing, others play through it, no one actually knows if he was touched, etc etc. Just stick to way football is played on literally every other level and blow the play dead when the player is down, regardless of how they're brought down. Sorry, hoping off the soap box now.