We might not want to stop his free speech rights. If he has been given a spot to speak, then he should be allowed to do so. Protesting him during the speech seems to also be a free speech issue.
Romney can give his free speech anywhere he wants to.
If he is allowed to give it under a Tea Party Express banner, clearly a photo-op, then it is a tacit endorsement of Romney by the Tea Party Express.
My issue is with the Tea Party Express. It is salvagable. Mitt Romney is not salvagable.