It was a misunderstanding. They were escorted out, for their safety, but an apology was issued from the stage, and they were free to return. My understanding was that they instead went down to torment the other side.
IMO, signs need to be clear about who you are. Protest Warriors might be clever in their sign design, but not clearly on one side or the other.
At demonstrations, polarized emotions are already running high, and people evaluate each other quickly based on signs and symbols. IMO again, Protest Warriors are adding to confusion rather than clarity.
I've been trying to comprehend the "misunderstanding" since I first saw the picture last night, and can't. Whoever the moron(s) was we don't need them on our side.