But she is such a cutie
Plus the entire human (real) population is all doomed without a battlestar to defend them so why not go all out for one last mission of glory instead of floating in outer space until Cavil's fleet inevitably finds and destroys them.
As genuinely heartfelt as these new cylons that have aligned themselves with the humans seem to make themselves out to be, I have no doubt they'd leave in a split second when Galactica falls apart. They know they are capable of reproduction within themselves, they really have no need to stick around with a bunch of dead weight...