The fact that the former was meant to be private doesn't grant it a reasonable expectation of privacy. When you're in a public place where you're likely to be overhead, don't expect privacy.

More importantly, the issue of privacy is irrelevant to what I was saying. In one situation, you're attending an event and someone is ruining that experience for you. In the other situation, you're reading someone's content by choice.

Lastly, I'd like to make it clear that I'm not actually claiming that Adria is or isn't a hypocrite; I've read her blog post and her comments and I have my own opinions on her. I'm claiming that the above argument is not valid when trying to call her a hypocrite.

It is relevant. The entire predicate of this situation was that she is offended by such jokes because they oppress women (a bizarre and utterly arbitrary conclusion, by the way). If an overheard joke made between friends is oppressive to women in her view, then a public tweet of the same nature must also be oppressive to women. It's hypocrisy made plain.