There is a certain amount of “Because we’re right, dammit” attitude from Republicans, and groups supporting Democrats can engineer episodes like this to make them look bad. Politicking from the left is all about how things can be made to look, not how they actually are. Accepting such invitations is an individual political risk. A decade of Republicans accepting such invitations and pleasantly articulating their views would be good for the party and for its best ideas, but each individual candidate sets himself up for news video of minorities booing him or her, and being asked trapping, dishonest questions that can be spun against them.
That said, Republicans need to field candidates who will take those risks. In similar fashion, we should expect Democratic candidates to speak to unsympathetic groups as well. Such things are part of leadership.
