Can I use a GC Loader to run LoZ: TWW on original hardware or does that still count as an emulation?

You can use neogamma, you cannot use nintendont, as nintendont has faster load times. You must use a disc of the game, as WW was never released digitally. If you use anything other than neogamma, it would count as emulation, which is allowed up to a certain cutoff for each category.

But Shouldn't Swiss be okay aswell, considering the fact that it specifically launches the game in gamecube mode? For instance the tp SD leaderbord accept runs that launch the disc via neogamma and Swiss.