I think any violence is a safeguarding concern and that person should lose any privileged role of working with children.
I would not want anyone near my children who had violence and in this case it is especially concerning as it is an attack by someone more powerful, a person. This would concern me more than someone convicted of violence who was in a fight once where it wasn’t clear they had provoked it for example.
There is also evidence that cruelty towards animals is linked to cruelty in other areas of life. It’s a safeguarding concern pure and simple.
Perhaps if they went to ‘rehab’ type anti violence sessions or whatever then in a certain amount of years of probation they could be let register again as a teacher. That’s my view anyway.
Perhaps I’m more sensitive as my child has high SEN and this would worry me a lot if it was his teacher.