No one excluded women or made them feel unwelcome. The slides said nothing offensive about women. Women may have been disproportionately offended by them, but that is not the same thing. Anyone who is offended by the presentation is offended because they have adopted beliefs and values which lead them to be offended.
If the community is actively excluding women (e.g., not allowing them to participate or treating them badly when they do), that's a completely different matter.
They portrayed women as sex objects rather than living persons with minds of their own. They say to women, "we're more interested in your tits and ass than in any code you might have to write." You didn't get the message, and it may not have even been intended by the presenter, but the message was there, loud and clear.
Those of us who are interested in precise communication (which, in my experience, usually includes hackers) are usually more than willing to criticize someone for miscommunicating. If I go around saying "functional programming" when I really mean "procedural programming", somebody is going to stop me and correct my usage. And if I refuse to listen, the fault is my own. This is no different. If you don't want to broadcast misogynistic messages, don't use misogynistic visual language.
No, the talk portrayed porn stars as sex objects. The comparison was explicitly "bad database" == "ugly porn star", "good database" == "pretty porn star". You can't demand precise communication in one paragraph and then drastically read hidden meanings into things in another paragraph.
Besides, you would never demand the same level of precision in visual aids if he used lolcats rather than porn stars. I think that precise communication is simply a posthoc justification for your gut reaction.
Come to think of it, it's not necessarily a matter of precise communication. The fact is, the vast majority of women who saw that presentation got the sense of being unwelcome and objectified. I think you can measure just about any attempt at communication by the message that actually gets across to people, and the message that actually got across to women was what it was. That's the point of the whole article.
Why did the women in the article perceive it differently from you? Maybe because when you're a victim of systemic sexism every day of your life you're better at recognizing it, and when you're the beneficiary of systemic sexism every day of your life, you're better at ignoring it. That's the standard explanation at least, and there's merit to it.
If the community is actively excluding women (e.g., not allowing them to participate or treating them badly when they do), that's a completely different matter.