Context: a while ago Brianna Wu was accused of faking threats against her when she posted something to a Steam forum under her name saying "come at me, KiA." The thread was deleted, but people caught on and Encyclopedia Dramatica tweeted about it.
Naturally, GamerGate and other similar trolls ate it up, accepting the evidence uncritically. But like the vast majority of their allegations, there was another entirely plausible explanation.
As the controversy unfolded, Brianna Wu addressed the allegations under her alternate account, . (EDIT: The account has since been closed shortly after writing this Storify.)
Naturally, GamerGate completely ignored this alibi because that wouldn't give them another reason to attack a woman they already hated.