Well it's not fair for H & M to do character assassinations of their family members is it. There have been all sorts of allegations made about racism, a total lack of concern for M's and H's mental health problems, not being financially supported, Archie being denied the title of Prince which he cannot be given until Charles becomes king, and let's not forget the 'wedding' that took place 3 days before what the world was led to believe was the actual wedding.
Their family members shouldn't be "fair game for all sorts of malicious comments. They are real people, not cartoon characters to be made of fun of despite what (H, M and others) think of what they have done" even if they've actually done what they're being accused of.
I have no idea how I would "feel if a bunch of strangers were writing all kinds of false rumours about (me) as if they were true" but I can imagine how the RF feel, having been on the receiving end of the lies from my own son and his wife.
Let's face it, what strangers may say about you is nothing compared to the pain that's caused when "all sorts of allegations" are made by the GS, son and brother whose loved, and not just said privately but to the entire world.
It might do some good if he were to read it. It might give him the wake up call he needs before it's too late to repair the damage he's done to his relationship with his family, if it isn't too late already.