I understand why people are dissatisfied - at the first major event promoting atheism and science, we are touchy about the face we present to the world. We want to make sure we communicate our values effectively to the rest of the nation and we fear guilt by association.
Is the answer to create a litmus or purity test for speakers? I think not. Certainly, we do need to have some standards and I imagine that the organizers of the rally do have some criteria laid out. I am sure that they didn't just slap this together hastily with no thought or concern for the outcome.
So what are we to do when people get up on the stage that we don't necessarily agree with or like? Here's my suggestion: we listen to them. We show that we aren't afraid of things we don't like. We show that we are strong enough and sure enough to let them have their say. If they are rational and supportive of reason, we may applaud.
But if they get up and say irrational things, if they get up and lie, if they get up on stage (or video) and betray the cause of science and reason, we let them know about it. We either withhold applause (can you imagine the national mall with thousands of people draped by an awkward silence?) or else we bring back the time-honored tradition of boo and hiss. Politeness be damned. Show the world how you feel.
We are a people who support free speech. Let's show the world how it works.