Five yard penalty every time a defensive injury prevents the offense from lining up. Offense has to be moving to line up immediately after play. Wouldn't be enforced on clock stopping plays (incomplete passes, out of bounds, etc.). Each team gets 5 30-second time outs per half (get rid of all the TV bs every time out), and time outs can be used to avoid the defensive penalty.
Defensive penalties (real or fake) take away a HUGE advantage to the offense trying to push up tempo. No reason to penalize the offense because the defense gets hurt and would negate all the faking. It's basically treating like you used to see the big fat lineman that couldn't get back on sides before the snap after a big completion.
Soccer, baseball, basketball, literally no other sport stops the offense immediately for an injury. It is too unfair and (as we now see when we play duke and state) leads to 20 fake injuries a game. They wouldn't do it if it wasn't a HUGE advantage. If you think about it five yards is not unreasonable at all. Otherwise may as well just say the QB can't say hike until the defense says they're all set up and ready to go.
You're going to penalize the defense 5 yards because one of its players has a broken leg ?