In short, the mother demanded that UA provide a hot meal (no hot food was catered or scheduled for the cabin in which they were seated) for the daughter and told a flight attendant that her daughter would "have a complete meltdown and start scratching" if it were not provided. In other words, a threat was made to the crew of violence if the meal - which the parent failed to provide for - was not forthcoming. I think that the mother made the decision to divert and remove by making the threat.