I read more about it and apparently they just kept the mic for 30 minutes. My assumption was that they wanted to speak for a few minutes and letting them go on would have been better than a big shouting match, but that was wrong.

I think everybody is talking about their actual message far more than if they grabbed and held the mic from any other candidate.

The argument has been made that they miscalculated by taking over the stage of arguably their best ally (which may or may not be saying much) running for POTUS.

I am not sure that I agree. My gut tells me that this was a comparative win for their message, including taking into account all of the liberal rage at their choice of stage.