If Rutan and co. do get some sort of FAA waiver to let them take up paying customers without meeting the usual certifications, that would really open them up to lawsuits should something go wrong. It'd be extremely easy to argue that Scaled failed to meet the usual standards for safety -- and so obviously couldn't meet them that they didn't even try to get certified. Yes, people would sign waivers, but those don't mean a whole lot.

You'd probably need some sort of legislation creating a special category of vehicles that are considered experimental and thus have to meet a much less stringent set of requirements, that are allowed to carry paying customers on demonstration flights over unopopulated areas, and which have some special immunity from lawsuits (so long as they properly explained all the risks to the customers).

That may not be such a big hurdle, though. I don't think such legislation is a bad idea, and I think it's politically possible as long as the scope of such flights is drawn pretty narrowly.