Just like the federal government, there is no molehill so small that a FA can't turn it into a mountain. If memory serves, it takes 3 or maybe all FAs to agree that a passenger has been disruptive enough to have the passenger pulled from the flight. Either this captain overreacted, or he was given really bad information, or both.

As has been pointed out, there is my story, your story, and what really happened, so we'll probably never really know. Hope for the captain's sake that his decisions were deemed reasonable.