Violently suppressing peaceful protestors is my guess.

To make it look like the protestors are violent. They wouldn’t call in those troops if it weren’t for those savage antisemitic protestors, right?!?

Great question.

It’s hard to crack down on dissent without them.

Depending on your biases, either to try and maintain order to prevent it from becoming a riot, or to intimidate and assault protestors.

Given the history of police and protesting college kids, it’s probably supposed to be mostly an intimidation thing.