If Sir Simon wanted to protect Professor Arday's mental health, circulating a letter which accused anyone who had doubts about his research of racism was pretty much the worst thing he could possibly have done.
No one is in academia for the money. Almost no one is in academia for the prestige. The only reason to be in academia is because you have a compulsive need to pursue the truth. If we can't call out bad actors, what are we even doing?