That would still be a TD so long as he broke the plane before touching the ground with any body part besides his hands or feet. From the NFL Rule book :That makes no sense (though I understand the protecting the QB angle), because if the QB is running for the end zone and dives for the score and barely crosses the line, that should be a TD. But this rule would spot the ball at the 2 or wherever he started to dive from.
when a runner declares himself down by:
- falling to the ground, or kneeling, and clearly making no immediate effort to advance.
- sliding. When a runner slides feet or head first, or simulates sliding the ball is dead the instant he touches the ground with anything other than his hands or his feet, or begins to simulate touching the ground;