What is not justified is insisting on debating semantics when you know and understand perfectly well what they mean by racism by now.
A word can have multiple meanings. Insisting other people use your prefered definition - something both sides are guilty of - is nothing short of a distraction from actually discussing any sort of substantive issue.
Firstly, the only reason racism is being discussed here at all is because of semantics, and, more specifically, the similarity between the semantic debates around the word 'racism' and those around the words 'misogyny' and 'sexism'.
Secondly, and once again, my essential point is that, for the internet at large, the question of misogyny has become one of semantics, because there is a movement to expand its definition for rhetorical reasons, and to insist that everybody else uses that definition, so as to silence dissenting voices*.
Thirdly, what you seem to be missing here is that a discussion of the semantics behind a subject is, by necessity, a discussion of the subject itself**. I've seen smart feminists deliberately using controversial definitions to provoke and open up this kind of debate, and that's a good, positive thing. What is not good or positive is where people try to shut down debate by demanding that issues of semantics be taken off the table, and their chosen definitions be accepted without question (when they say, for example, 'your definition is just wrong').
*There is also the matter of 'misogyny' more narrowly defined. Feel free to try and start a discussion on such overtly reprehensible attitudes. Personally, I think what's to be said about them is so obvious as to be uninteresting.
**Note how, in my previous post, the bulk of what I said was directly engaged with matters of actual racism and its effects.
Substantive issue in this case being that, whatever you call them, insisting on trying to compare the two phenomenon here (Whenter you call the first institutionalized racism or racism, and whether you call the second "violence-resulting-from-racism" or "Racism against whites") as if they were similar phenomenons is either uninformed or hypocritical.
But they are similar phenomena. Very similar. In each case they involve the perception that race is a relevant characteristic, and that negative attitudes or treatment towards a particular person or persons are justified on the basis of their membership of what is perceived as a racial group. The question of what causes those perceptions in any given case - and the way in which they are conditioned by the experience of living in a racialised society - is something that ought to be engaged with and discussed, not shoved into neat little boxes based on the 'race' of the persons in question.