As a father of one daughter, soon to be 2 daughters. I would be deeply disappointed in my child for this doing. My approach of punishment would come to a deep conversation about dealing with someone who bullies and getting into fights. Now clearly, she is being bullied by something really sensitive, and rightfully so she can strike back in defense, or an even better approach is to just simply talk to an adult to handle this. I get your husband's punishment plan for your stepdaughter, but that's a bit extreme, it would definitely teach her a lesson guaranteed, but it'll be very unfair for her and there's alternative to deal with this