Are luthiers allowed to make shortscale Warwick or Spector copies? But with a different headstock?

It is the cosmetic. That's like asking why so many on this forum and others have had luthiers build basses/guitars that copied the Strat/P body or the Jazz body.

I know what I like. And what will make the bass unique to me is the features, color, wood choice, and small body changes (though it would still look like an NS/Streamer)

Thanks for the reply though.
Yeah, I don't think this will be a problem if you can find a builder to build it for you to your specs...