That's because many people here are not merely "working against him in the primaries", but threatening/promising that they would vote against him in the general election if he won the nomination.
This is either (1) completely stupid, or (2) a total bluff, a metaphorical "suicide threat", an attempt at a circular, bootstrapped argument against Giuliani in the primaries ("you better not vote for him now because, um, if you do I'll throw the election to Hillary"), invented by people who have no real argument against him.
In either case the people saying this deserve to have their arguments shot down and scorn heaped upon them. Whether the shoe fits you is for you to say.
Get a life! We're in the primaries!