I think the OP means that calling it sideloading gives it a sneaky dark connotation which it doesn't deserve because installing software is simply a normal thin

I think the OP means that calling it sideloading gives it a sneaky dark connotation which it doesn't deserve because installing software is simply a normal thing for a user to do. It's Google that's branding it as such because they want people to only trust the play store, and thus protect their 30% stake and other benefits like deciding what goes in the store.