Re: Very surprising.
I'm not surprised by this turn of events. Groups like Anonymous and splinter Lulzsec might pretend to be "anonymous" but ultimately they have a inner circle of organisers, a surrounding ring of soldiers and then an outer cloud of hangers on. It may be anonymous but it's no different from any other gang.
If you can get into the inner circle you are in a good position to identify who the others are. I assume they turned Sabu because someone either informed or he made some stupid mistake and used the intervening time to identify the rest of the circle and ensure there was enough evidence to charge them with something.