I'm sure people have been playing Nc6 + b4 in Sicilian before Kasparov
- altough maybe not in that exact position.
In your game white maybe could consider 15. Nxc6 Bxc6 (15... bxc3 16. Nxe7+ Kh8 17. Qxd6) 16. axb4 altough black probably should still have attacking chances on the queenside. In Adams-Kasparov this obviously was impossible.
I studied this game a lot and quite like the idea of Nc6 and a quick b4, and used it in one of my games below.