I have never heard of anyone describing M in those terms in any book, interview, anywhere. What most seem to say is that he enigmatic, aloof... somewhat removed from the social element of the industry and private, and that doesn't always go down well.
I remember a Smiths era story where someone said that because M didn't socialise with the crew or the sound techs or anything, they couldn't really relax around him - they were always on eggshells. He was quiet and awkward, and there was a sense that only Johnny understood him so if you wanted something, best to go through Johnny first.
Some people just do not understand introverts and they take this stuff as a personal snub when it isn't at all. Especially when you're a "pop star" and you're expected to be on display, I think that aloof quality can look like rudeness. There have been so many stories on here where M has been cornered by showbiz types in a pub or in a supermarket trying to get on with his day and has ended up giving them a fake phone number and doing a runner. That's totally understandable and relatable to me, not odious.