You've just proven it's easy to convince yourself of something that's obviously not true simply by creating a narrative and tying some minor details into it.
Sarkeesian needs to screenshot a Twitter user who over the last few minutes is sending her death threats. She's getting notifications every few seconds from Twitter on her mobile device, presumably her phone. She knows how to make a screenshot on a computer, and it'll capture more tweets than the four or five you can typically see on a mobile phone, so she fires up a web browser, goes to the Twitter URL of the harasser who's still in the process of sending her death threats, hits Ctrl-PtSc, and then sends the screenshot somewhere.
Completely normal. Exactly what you'd expect someone to do (I know it's technically possible to take a screenshot on your phone, but (1) you won't get many tweets and (2) personally I don't actually know how to do it, if I were in the same situation I'd have to Google for the information.)
Your idiot evidence tries to make every element of this suspicious. They... *gasp* went to a PC they weren't logged into to make the screenshot. They *horror* didn't wait until the death threat stream had finished before making the screenshot, meaning some were coming in seconds before she took it! Because you've decided she must be making this up, you've had to invent a ridiculous narrative involving tablets and logging out of PCs that has Sarkeesian apparently unaware she can have two browsers on the PC that has a keyboard.
What's even more bizarre is you make these allegations while GamerGate simultaneously acknowledges that Sarkeesian does, actually, get death threats all the time. The GG "Anti-Harassment Patrol" even trumpeted it's "success" at finding a certain Brazillian journalist who is one source of anti-Sarkeesian death threats, and got terribly upset when Sarkeesian said "Yes, I know, I've already reported him" and spun it as "Sarkeesian refuses to report harasser we found!!!1!!"
GamerGate is about harassment. Stop trying to cover it up.