Turns out that you need to get 5 million points to get 5 stars on the game selection screen. I think this should be a requirement for the 100% category as that is more of "completeing" the game.

That's just a rating. The same mechanic is used in Super Mario Advance 4: Super Mario Bros. 3.

Spyro 2 100% does not require skill points. Spyro 3 117% does not require skill points. Crash 3 105% does not require platinum relics (or dev times). Banjo-Kazooie 100% does not require all Mumbo Tokens. Donkey Kong 64 101% does not require all coin pickups (or even all small bananas!).

Every speedgame is different. Yes, you would be able to list just as many counterpoints to this. I don't think requiring a high score would be realistic for a speedrun. If the 5 million points / 5 stars unlocked like an extra stage IN THE GAME, then sure, I could obviously see it being a requirement. As it stands, I don't think the category requirements will change.