So, history lesson. Queen Isabel of Castille, along with her husband King Ferdinand of Aragon, ruled the newly unified kingdom of Spain during the late 15th century. The two are famous for completing the reconquista and driving the Muslim Moors out of the Iberian peninsula, approving the creation of the Spanish Inquisition to torture and murder all non-Christians in the kingdom, issuing the Edict of Expulsion that forbid all non-Christians from Spanish citizenship, and financing Christopher Columbus' expedition to the Americas and thus beginning the nascent Spanish kingdom's growth into a brutal colonialist world power.
For any other self-proclaimed advocate of leftist causes, changing one's name to Isabel would be an ill-advised mistake. In Phil's case, it's entirely appropriate.