It has surprised me how many guys, even guys in different countries, have attempted to pick me up in one form or another on Twitter. That's just my experience as an attractive young white woman who generally doesn't post anything controversial, political, or really in general very interesting if you don't know me or the context of the tweets. I'd absolutely say it's mostly harmless and nothing like the author has experienced, but it does strike me that simply existing on Twitter as a female causes one to have a vastly different experience than a guy would. (Maybe I'm wrong. Any guys on Twitter willing to speak up? Anyone had a guy from another country develop a massive crush on you simply from reading your 140-character-or-less quips? Who then doesn't understand why you tell him his whole affection thing is totally pointless? He wasn't a bad guy; he didn't harass me or make me feel uncomfortable. But it was weird. That's probably the most extreme case of my Twitter-crush-people.)
I absolutely cannot imagine what a WoC who expresses actual, valid opinions on controversial topics and in response to highly visible tweets experiences. I'm sure it really sucks. I wish trolls on the internet weren't like that - didn't exist, basically.
Twitter definitely needs better block mechanisms, while we're at it.