I noticed that GSC/HGSS runs go to red. So why don't Emerald runs go to Steven, or at least have a Steven% category?

Just hypothetical.

i think steven is considered post-game content, were kanto and red are like a second act to the game

As the above, beating Steven is just one extra fight, doesn't really add anything to the existing Glitchless run.

Feel free to try it though, would make an interesting addition to your glitchless run.

New category? Stephen%? Any.1%?