Ebbie, there's a page on the laws at the website Tweed linked to. It says the fossilised walrus ivory pre-dates the 1972 law, so is exempt.

I wonder just how much of a difference to the sound the bridge pins alone make. A guy at my local guitar shop said they wouldn't make any difference and the pins were mainly just cosmetic/prestige. I think he's wrong, but I suspect the difference in sound wouldn't be very detectable by most people. Fossilised ivory is also quite expensive - not a big bang/buck ratio. Even getting the whole set-up wouldn't matter with my level of playing. With JP's skill level, it could very well be a Big Deal.