I thought people with 100k+ followers get trolled like this daily, especially if they dont hide their controversial political opinions, thats a magnet for trolls.. Block/report to the police and move on.. Seems like the situation is far better than I thought - from her tweet it seems like this is a rare situation that does not normally happen every day, thats why it was worthwhile to make a tweet about it.
The difference is that someone like Tim Schafer can say "look at this video, it's important and you should listen to what this person says", and get lots of responses along the lines of "Oh no, the feminists got to you too!", while when Anita Sarkeesian does it, she gets threatened with rape, murder, identity theft, gets called a whore, a slut, gets told to stay in the kitchen and other fun things.
And yeah, "block/report and move on" is easier said than done. If a large part of your daily interactions with people consisted of them screaming abuse at you, sooner or later it's going to take a toll on your psyche.