Don't make the mistake of confusing the word most with the word all when considering what happens in mergers and acquisitions. The application of natural selection to these situations is apt.

Consider both TechCrunch and The Huffington Post pre-sale to AOL. Which one would you have said made sense and which would you have said not-in-a-million-years? The TechCrunch acquisition was to literally buy credibility, whereas the Huffington Post purchase was to resource a strategy. Arianna Huffington makes AOL stronger in the traits that it has self-selected for. She's going to be just fine.

Arianna was the one who announced that Arrington would no longer be doing TechCrunch now that he was doing CrunchFund. The higher-ups at AOL were apparently on board with the plan for him to do both up until then.

I don't have any inside information, but one possible interpretation is that Arianna made this announcement to effectively force AOL to choose to either back her or back Arrington. They seem to have backed her, which has strengthened her control over the content engine that more or less drives the current AOL. With both Arrington and Topolsky gone (along with much of Topolsky's team), there's really not anyone there with the stature to challenge her in this area.

Honestly, it looks like she could be positioning herself to be the successor when Armstrong gets the boot for the current straits AOL finds itself in. Why leave the company when you can just run it?

Edit: Huffington clarifying Arrington's (non-)role: http://www.businessinsider.com/mike-arrington-no-longer-work...