Why is a professional event even seen as "an opportunity for a casual hook up"?
To say that flirting is "natural" is quite a claim; while it might be prevalent in our culture, that doesn't mean it's natural.
Conferences are both professional and social. In fact, it's hard to think of anything that is purely professional. People form short- and long-term relationships through all sorts of initial meetings.
I don't see any women saying "all flirting all is wrong at a conference". I see them saying they don't want to be harassed. The two things are not the same. I've talked to women at length about these issues and I've championed the adoption of strong anti-harassment policies at conferences I speak at (http://blog.urth.org/2011/09/05/conference-code-of-conduct-c...).
Maybe we just have different definitions of flirting. To get back to the original article, the Twitter exchange that it highlights is not flirting. It's just a man being an asshole. I also note that the article makes no mention of the word "flirt". It talks about "harassment", "groping", and "sexism".
There's nothing inherently wrong with flirting at a conference. Flirting is a very natural type of interaction for people, and asking people to not do it at all doesn't seem realistic.
However, men should not assume that flirting means that a woman is inviting you to touch her or sleep with her. In fact, she may not even be flirting. Men often misinterpret simple friendliness as sexual interest.
Be conservative in what you say and do. At a professional event, it is far better to miss an opportunity for a casual hook up than to be aggressive and make the conference an unwelcoming place for women.