It's weird, the first year the Honda S2000 came out...you could get white exterior with red interior. But the following years that color combo wasn't available. Don't know if it was a special edition kind of thing or not enough people bought it. They still offer silver with red though.
I don't see why BMW would not let you choose this color combo because (correct me if I'm wrong) you can get the e46 M3 in that combination.
Add: I just tried it on
www.bmwusa.com and it allowed it. Usually they have an interior color 'x'ed out if it's not allowed.