Surely they were there for protection, the cops, acting as escorts in the event of any type of exit, good, bad or mad.
Then you would have to ignore what Brett said their plan was. He specifically they were prepared to escort Trump from the stage. No such statement was made about any of the other candidates. If you remember Brett led off with the loyalty oath demand with the express purpose of embarrassing Trump. Consider now how many republican figures have sworn they would not vote forTrump if he wins the nomination.