Suggesting that it's ok to accept that automatically thinking a woman at a trade show is not an engineer is simply irrational. We are humans and with that comes the ability to override animal thinking. Dare I say, I expect the person to have that thought to override it, think rationally, and say something other than what most of them do? And is asking for that somehow in and of itself irrational? Look, having heard these bullshit arguments hundreds of times, I am right tired of having them. We've been discussing this issue long enough that the people who keep doing this, need to not be tolerated. We need to stop expecting those without power to always be the ones to take the high road.
Anger is a valid and rational response to continued discrimination. To say otherwise comes dangerously close to tone policing.