I don't think this is a very good characterization of the debate. Most importantly, the debate as far as I can tell centers around whether or not it is appropriate for your livelihood and access to healthcare to be at the mercy of a Twitter mob, specifically about whether or not threatening someone's livelihood, etc (namely by way of harassment campaign against one's employer) constitutes 'free speech'--more abstractly, the debate is about whether or not threats and harassment constitute free speech.

Further, I don't think the cancel culture debate is about the Overton Window as much as rank partisanship. For example, I don't think progressives would argue that nonviolent protest falls afoul of their OW, but they canceled (and defend the canceling of) a data scientist who so transgressed. Similarly, do progressives really think it's so offensive to publish a quote from a black man in the context of BLM in which he wished for more attention to other problems his community faces--is that actually outside of their OW, or is it more likely that the journalist's crime was publishing a viewpoint that failed to toe the ideological line? Similarly, the Hispanic utility worker who accidentally and absent-mindedly made the "OK" gesture from his truck--whose Overton window is that out-of-bounds of? Or the professor who said a Chinese word in appropriate context which sounded sort of like the N-word? Are these really outside of people's Overton window, or is this just overt bullying? In the other direction, the sitting Prime Minister of Canada has dressed in blackface so often that he's admittedly lost track, but he was somehow not cancelled? Is blackface really within the left-wing Overton Window, or are we observing ideological partisanship?

EDIT: Downvoters, I'm really interested in hearing your opinions!