Can someone believe in racial supremacy without being racist?

No.
To believe one group of people is superior than another because of their skin colour is racism.

No, I don’t think they can. If they believe certain people are superior or should always be in charge based solely upon racial characteristics, that is basically the definition of racism. Whether or not they act upon those beliefs only determines whether or not they’re dangerous.

if it looks like a duck and walks like a duck, it is a duck.

Isn't the belief in racial supremacy part of the definition of being racist?

No, but I've some SW'ers try to do that, but when it comes down to it, they are racist as fuck.

No. As others have pointed out, believing in overall superiority based on "race" only is the very definition racism.
I believe...know that there are varying degrees of racism. I believe that most people harbor at least a smidge of it, even if they are not aware.

Those who embrace and fortify those feeling in themselves and others as opposed to questioning and repudiating them, are rascists.

Can you drown out politics without being evil?

No

Of course not! Such beliefs would condition their every thought and interaction that involved those in the out group.

Maybe, but would they then be a race traitor for not acting on their beliefs?

No.

The Order of Louis Farrakhan, The Order of Al Sharpton, The Order of Joe Biden.

No they're literally the same thing (it's all in your mind), regardless of whether you act on what is in your mind ... the acts are derivative of the belief/thoughts

In contrast if a 2 year old called someone a slur just because it was a random vocalization they had overheard before and they were merely repeating a random sound, and they had no idea it actually meant something, there is no belief upon which to act, and no intent to be negative ... after they learn what it means, if the action continues, then that's another matter