I would not have reacted the same way in this set of circumstances -- I feel sort of bad for those dudes wondering why their picture was being taken -- but I am far from "furious" with Adria. I will, on the other hand, never do business with SendGrid.
I worked with a bright, lovely young woman who had taken two terms of Java, with an eye toward a CS degree. One of her professors told her in office hours that she smelled really good. So she was doing marketing. Little creep-outs can have a huge impact, and you will unfortunately find so many of them in nearly every tech setting that if you hang in there, you just get accustomed to saying nothing. But saying nothing is not the ideal course of action, because based on the numbers, lots of women don't hang in there. Adria is right that the little girl on the slide might never make it to PyCon (in a dev role...) if things stay the same.
Imagine if roles were reversed, and lucrative, enjoyable, interesting jobs were mostly held by straight women, and every time you went to a professional conference, you had to endure non sequitur pictures of men in bikinis, and uninformed, under-dressed plastic booth bros, and people assuming you're an uninformed booth bro no matter how you look, and the after-party at a male strip club, and countless unattractive old women chatting you up when you'd rather write code and all manner of little, alienating crap. In this bizarro world, you would likely not believe the sense of relief when another man spoke up about all this stuff that had gone unquestioned.
Your comment about feeling uncomfortable around Adria is ironic, given that feeling uncomfortable is exactly what Adria was trying, however imperfectly, to fix. Unfortunately, the comfort of straight white men has again ruled the day, and SendGrid fired a black woman to preserve it. I hope she finds a truly wonderful lawyer.