While it hasn't yet been resolved as to whether or not it should be a distinct ability, or should be defined based on what it does, add to battle is certainly not by default a band ability. So YMT is correct. I would say based on the current status quo (where add to battle can be a band ability if it does band) that if you band Hosea into battle after Egyptian Magicians or Nebuchadnezzar brings in another character, they could be captured, since their ability would make them a banding ability.