I like Regardie, but I don't care enough to argue about him.
I am, however, thinking about Mosh's anus.
Well, I'm partly going by what others have said about him, but I never liked any of his interpretations of Crowley's writings, especially the bullshit notes he wrote about The Book of Lies.
I'd take anything he wrote about Crowley and his writing with a grain of salt anyway.
When Crolwey couldn't afford to keep him around as his secretary anymore, they had a falling out (as Crowley seemed to have with everyone close to him anyway) and there was plenty of bad blood. Then in his later life he seemed to take on a sort of apologist role against Crowley's detractors/try to sanitize some of Crowley.
I also wouldn't pay much attention to what he wrote about Crowley's writings in anything beyond an editorial capacity because he was pretty adamant that he wasn't into Thelema.