I can't say I've ever seen anything like that before, but it seems fairly specific to the Tush Push - a play some owners still would like to ban - too. If you just made it illegal for anyone to launch themselves into the air over their own defensive line that would take care of the injury risk. It's not like you see it that often. I'm sure the Lavar Leap (which was a 4th and short but not near the goal line) could have ended with a bad injury too. Difference is he was not actually offsides. But you could ban making yourself into an airborne tackling projectile for the same reasons hits to the head are banned.
I think the rule that already exists is probably sufficient, but it should be an automatic TD after just the second time, and it shouldn't be specific to one player (had Luvu committed the third penalty that would have already done it this time).
Also Luvu had been told he was going to receive an unsportsmanlike the next time, which would have been assessed after the touchdown.