I don't think there is any further explanation needed than what we got: Gaeta, Zarek, and the rest of the mutineers were pissed as hell that their supposed leaders were in bed with the Cylons. The Pegasus
crew harbored a particularly strong enmity for Cylons, nurtured by Admiral Cain, which no doubt stuck around long after Pegasus
herself was lost.
I don't see why their mutual assassination plots would ever be discussed again after both Cain and Adama declined to give the kill orders.