There is a case to be made that nominating Mitt Romney, even if
insincere, would be better for social conservatives than nominating
openly pro-choice, pro-domestic partnership Rudy Giuliani.
Nominating Romney, who was forced to abandon his pro-choice
position and other socially moderate/liberal views, could be seen
as a sign of social conservative power within the party. Nominating
Giuliani, who would be the first pro-choice Republican presidential
nominee since the religious right became a well organized GOP
faction, could be interpreted as a sign of social conservative
weakness.
I'm not sure I'm persuaded by this case, but there it is.