All political parties must in words and deeds eschew violence. Anything else is fascism or some such totalitarian ideology grasping to seize power by any means possible. Inevitably it attracts like and the leadership soon beats others into submission.
Every such organization funnels the violence into a front organization in order to keep their political skirts clean. It is their silence and lack of action to prevent such activity that confirms their intent.
The Egyptian military is not stupid either. They let them hang themselves before they rounded up the activists once again and effectively banned the party.
Egypt perhaps now has a chance to properly evolve sectarian political parties who produce real public support. That would be welcome.