Big mistake was telling the agents about the incorrect name...
Yah, I wonder how the story went. They told about incorrect name, but asked for seat anyway, but then FAs kicked them out bec didn't have enough seats?
Either way, I absolutely do sympathize with the customers here. Obviously, this is nothing like the other story, but this is the type of routine abusive nonsense that you always deal with when you fly.
Particularly if they owned up to the fact that older son wasn't on flight and <2 son was going to sit in his seat. It's completely unreasonable for the airline to deny them that seat, and to make it a criminal matter is figuratively criminal.