Law enforcement would love this too. Let's say you're a "meek mild-mannered reporter" (or whatever) by day and "super-hacktivist" by night. It wouldn't matter if you're using multiple layers of TOR/ONION or working via a compromised machine in China, a LEA would still be able to match your daytime work profile to your nighttime alter-ego.
This might start start an arms race. Given websites that analyse user keystrokes, would a random delay inserter work? Also, I assume that doing stuff like typing this comment into a separate text editor, then copy-pasting into the posting submission form might help cover your tracks.