Well, in the first place, I don't think there is any actual evidence that the 8 bil is earmarked for Las Vegas. So far, its just supposition.
Second, Las Vegas to LA is a perfectly reasonable city pair for high speed rail. Not at the top of my list, but a very good project. I am quite certain that the passenger loadings would be terrific. the terminus is apparently the showpiece Fullerton depot, so naturally the train gets described as a "train to Disneyland" by the naysayers. I'm pretty sure the proponents will get over the Maglev part pretty quickly.
Third, HSR isn't inconsistent with conventional rail. With the doubling of Amtrak's budget, there is money for conventional routes and they should do those too. We will be lucky to average one new HSR route a year if we keep funding at the current pace.
Fourth, Phil Gramm has zero credibility in this area. He was arguably the leading proponent of kookster capitalism that got us into this mess. His slash and burn approach to the federal budget in the early 1980's lead to the infrastructure and science deficit that we see today. Basically, he's a jerk and he has no business in public life, unless its to do public penance.