"The Letter" - blowback on Justice and Open Debate

It's not that often that I agree with much of what Globe columnist Marcus Gee writes - he lurks on the right margins of the paper's mainly middle-of-the-road politics - but I think he may have a point today, when he warns against letting a movement turn into an inquisition.
Perhaps his language is a little flamboyant for the matter in hand, but there does seem to be some evidence that we are approaching an age where all public personalities need to make a very public avowal that Black Lives Matter and that systemic racism is present in everything we do and say. To question this, or even to espouse it in a sufficiently luke-warm manner, is to risk outrage, condemnation and shaming, and sometimes to put an otherwise exemplary career at risk. Politically correct language has to be very carefully monitored, which may not be a bad thing in itself, but lapses are now indefensible. We have seen this with RCMP Commissioner Brenda Lucki (which I have already commented on at some length) and CBC broadcaster Wendy Mesley (who was put on leave for referencing a book title that happens to include what we now call "the N word"), among other examples.
The latest outpouring of scorn and vitriol has been aimed at a public Letter on Justice and Open Debate, now familiarly known on social media simply as "The Letter", published in Harper's Magazine and signed by 153 intellctuals and "cultural luminaries" from all ends of the political spectrum (and from none), including Margaret Atwood, Steven Pinker, Salman Rushdie, Malcolm Gladwell, Noam Chomsky, Wynton Marsalis, Gloria Steinem, JK Rowling, and many other household names (including - shock horror! - intellectuals of colour).
The letter decries the current climate of censoriousness, intolerance for alternative viewpoints, and a "blinding moral certainty".
It warns of a growing tide of illiberalism, and a weakening of "our norms of open debate and toleration of differences in favour of ideological conformity". It also warns against the growing spectre of what is now known as "cancel culture", the practice of withdrawing support from anyone who has done or said something considered offensive or objectionable under the current zeitgeist, denying them a speaking platform, and preferably ruining rheir careers (a good example being the summary dismissal of Steven Galloway from his UBC lecturing post for an accusation of which he was later exonerated). This leads to a guilty-until-proven-innocent attitude that is antithetical to democratic Western values.
Now, I'm not sure I necessarily agree with ALL of the letter myself, but it immediately met with a whole lot of dismissive moral certainty on social media, many of them ad hominem attacks on the signatories, rather than considered refutations of the letter's content, along the lines of "privileged whiners" and "hypocritical elites". There was also a more official response, entitled  A More Specific Letter on Justice and Open Debate, published on The Objective's website just a couple of days later, which takes the rather strange angle of guessing at specific incidents that may - or may not - have prompted the original letter and discussing them in detail (the original letter deliberately avoids specific instances because its whole point is the trends that we are seeing).
Of course, it didn't help the privileged whiners' cause that one of the signatories, Black historian Kerri Greenidge, retracted her endorsement of the original letter, claiming that she never gave permission, and another, trans writer Jennifer Boylan, asked for her signature to be removed when she found out the full list of signatories (it is assumed that she is objecting to being on the same list as JK Rowling, who has recently been accused of being anti-trans - this suggests that Ms. Boylan agrees with the content of the letter but is picky about who she wants to be associated with, not a very cool intellectual stance).
As Marcus Gee comments, "a revolution that becomes an inquisition risks losing the hearts and minds of ordinary people". This is partly about political correctness gone AWOL, but it is partly about just keeping perspective, or at least allowing perspective.