If you can show how it is possible to beat the hack with 16 stars as a senseful category while beating bowser then I'll be very glad to add 16 star but this is not gonna happen. If you would know this hack which I assume you do not even do you would know that the warp to bowser 3 replaces the cannon on the castle grounds and is not in the normal location from the original, so you either need to get 120 stars and get there or you get inside the cannon with 0 stars doing a very hard trick. 16 Star would make absolutely no sense here.
For the future I really recommend you to get to know how a hack's speedrun category options can even technically work before you request anything. 0 Star and 120 Star are the only categories in this to make sense and there is currently no way this can change.
Aesides ^that what Frosty said: Any kind of category on this site (most likely sm64romhacks) will never get added without you submitting a run of it, cause no one likes empty categories...
So if you at least would've tried that (to run it yourself on 16 Star) you would've noticed by yourself, it's not a thing...so yeah.