In practice, this is not how "racism" was interpreted colloquially for a good 30 years at least. Rather, it was interpreted as "racial bigotry", but with the savage bite of intense condemnation for a deep moral failing.

This "power only, and by the way, exactly as much power and under exactly the scope needed to make sure it only applies to whites" definition is a new prescriptive invention, and/or a return to historical usage (somewhat arguable, but at least a case can be made). It's a significant part of the reason why "racist" is losing its sting now, which in turn is part of the reason why personal racial bigotry is (apparently) rising again.

If "racist" and "racism" cannot be terms that can be used impartially and universally in easily-discerned situations, then we should stop using the term except in esoteric academic situations where we have the space to document the prerequisite factors, and pick some other term that means "your heart is filled with hate based on what someone looks like, not who they are" because that is worth the strongest type of condemnation.