Player behavior wise, making telebatons do a small amount of damage per baton isn't going to change much. If they're a verified antag, it's a tiny buff to the disarm->harm stunlock rotation. If they're a non-antag shitter, nobody will care if they take 15-20 points of brute on the stunlock trip to sec. If the head themselves is the shitter, damage isn't going to slow down the behavior, and it'll honestly be welcome as "not only do I get to lel stunlock, I get to hurt 'im too!".
Plus, you can still just baton and cuff.
I'd honestly just swap the telebaton for pepper spray and a flash. Pepperspray/flash makes more sense for a department head to be carrying, over the telememe baton.