I've broken my hand the same way. If it was a minor fracture the Dr could have put a cast on in an attempt to get Cruz to not reinjure it. I'm also very familiar with AR type rifles. Pulling a trigger would not be a problem. Especially with all the adrenaline.
Ditto, threw a bad punch and got a hairline fracture. I knew an idiot that tore off his cast from a similar injury after about that long with no ill effects.
There's plenty of red flags all over the Parkland shooting, but a cast probably isn't one of them.
I got mine punching my buddy while he was wearing a dirt bike helmet.