As an African-American, I can definately identify with your post. I've had people in business situations bring what you mention up right to my face. Personally, I think what Mike was saying kind of fits with this...That might be part of why he reacted as he did; if the attitude around the endeavor (what ever it may be) is about skill, then no one wonders about these other things. If the attitude is about more general attempts at gender norming, or race norming, or what ever other social engineering you might have in mind, then people will always wonder what the heck is really going on. And I should add that that doubt cuts both ways...I wasted a bit of time myself with that.
All I can say is...how ever anyone gets the job, the slot at the expo, whatever...make the most of the opportunities that come your way. Do your very best. That's the only way to remove doubt once it creeps in. I'm sure that the two women performing at the expo will leave no doubt in anyone's mind.