Regardless of whether it's accepted in some academic circles, I've yet to see a compelling argument for why it's necessary to alter the definition of racism (and "power plus prejudice" is a fairly recent alteration of the original and still widely-accepted definition of the word). We already have terms to differentiate between its various forms, (internalized, systematic, institutional/ingrained, casual, etc.), so the "there needs to be a different term!" argument really doesn't wash.
And, quite frankly, I might be a little less skeptical of this definition if it wasn't used almost exclusively as a red herring when someone is called out on their bigotry and hypocrisy.
Edit: Also, I do realize language changes over time, but we're talking about a forced redefinition here -- and one that has some pretty drastic implications, at that.