It doesn't matter where an idea like "slut shaming" comes from, what matters is the negative feeling associated with being "slut shamed" resonates with a lot of people.

To take the analogy seriously (not advisable), it's like saying, "money isn't valuable if it's laundered". Absurd and wrong; sure, laundered money is bad, but it's the laundering, not the money, that's the problem. If we stopped the laundering, the "money" is still worth what it's worth, but does the author suggest the people who put names to the feelings many people are experiencing should stop? No. The author suggests the ideas are "nonsensical" and doesn't elaborate.

It's just strange to me that the left has come to own the defense of minorities, but it's a narrative that both sides have totally bought into, and zealously attack/defend.

Why is it "liberal" to care about someone's feelings?!

People versed in the obscure academic language of the different branches of grievance studies, who, not only now have managed to obtain tenure for themselves and their disciples, but now are sending apostles into the industry to obtain power in those spheres as well. They are in charge of, and the only ones properly trained, to help regular people atone and repent for the original sin of privilege. They're being given progressively more say and power in academia, in the industry, while actually not dealing with anything backed by hard science or evidence-based research.

This is not to say that some of the causes of parts of the grievance priesthood are not worth fighting for, such as equality and inclusion, but that it's likely not about those causes anymore. It's now a self-replicating organism that is primarily interested in acquiring more authority. It's reminiscent of Christianity (as a value system) vs the Church (as an organization) tension that's existed for ages.