Eh, maybe I'm giving too much credit to the average person, but I don't think they'd be influenced enough to go out and buy bitcoin based on a celebrity endorsement.  Some people might, of course.  There are people who refuse to get their kids vaccinated because certain celebrities keep spouting ignorant nonsense about junk science, but they don't represent the majority and I doubt any celebrity endorsement of bitcoin would have much of an effect on adoption or price.

I'd still love to see a mainstream movie with bitcoin as a major plot point (or even a good indie flick).  I know there are some foreign films that at least mention it, but thus far there haven't been any big Hollywood productions that involve bitcoin in the storyline.  I think something like that would have more influence than a celebrity testifying to how great bitcoin is and what it can be used for.