This article didn't read like character assassination to me, personally - most of the time spent on GRC/SpinRite (after the overall topic of disk recovery is introduced) seems to be either observations about Gibson's style with which I think many would agree - e.g.

"It doesn't help that Steve Gibson's writing is pervaded by a certain sort of... hucksterism. A sort of ceaseless self-promotion that internet users associate mostly with travel influencers selling courses about how to make money as a travel influencer."

Or substantive critical points about the software, e.g.:

"This gives the flavor of the central problem with SpinRite: it claims to perform sophisticated analysis at a very low level of the drive's operation, but it claims to do that with hard drives that intentionally abstract away all of their low level details."

And I think it's fair to ask someone who is selling a piece of software for $89 to provide some backing for their claims beyond ones that would only pertain to largely-obsolete hardware.