Don't forget guys, that a few weeks ago Pegasus went to guns against Lee Adama and the Galactica. Let's not forget that tender moment where 4 of Pegasus' crew beat the tar out of Tirol and Helo. Finally, a Marine from Pegasus actually arrested Lee Adama in the middle of combat in the last episode. My point is that Pegasus is a pirate ship full of people used to a different form of diplomacy (rapes, beatings, stealing FTL drives and stranding people, executing helpless civilians, etc), and a wet-behind the ears son-of-the-Admiral, who just happens to come from a ship they hate, will never be able to gain their support; no one should ever be able to replace Cain and Fisk, although in the end how Adama works out to be Pegasus' commander is entirely up to the writers.
The smarter move would have been to promote yet someone else from within Pegasus. Besides, I find it hard to believe that Lee Adama is next in the line of succession after the Old Man and Tigh. If that's the extent of their senior staff, then they're really in trouble...
Now, for another picture of mah boy Lee Adama!