Y'know, I think I figured it out.
Anna first popped up early on in the trolling, when information was scarce and any source that had seen Chris in person was considered gold. With the exception of The Crazy Pacer, though, her information was almost always something the trolls already knew (such as Chris's homophobia). Anna vanished around the same time the trolls started to open lines of communication to Chris, only surfacing every now and then to snicker at Chris's antics.
But then Chris fled to Facebook, and it became harder for people he didn't already know to contact him. Around this time, Anna resurfaced--as Chris trusted her, she likely saw herself as having full control over all remaining lines to Chris.
So, being herself, she held a session with some of /cow/'s userbase. Her overall tone was pretty much "HA! I have full power over Chris, so if you EVER want new content again, you'll be nice to me and friend me on tumblr!". I've heard that she tried and failed to expose Jackie around the same time, too.
It seems that what makes her tick isn't trolls remorse or genuine concern for Chris, but rather a desire to be in a position of power over a large group of people.