Zappa was not an egomaniac, he was not abusive, he was not in it for the money. His interest strictly was to explore music and try to eek out a living at it.
he was definitely what might be uncharitably called a 'control freak', but since when was that a bad trait in a composer??
composers are organisers... they organise sound for a living - control freakery is a somewhat essential characteristic - I know if I was paying thousands of dollars to have my music played correctly, I'd insist on it being done exactly my way too...
I know FZ encouraged spontaneous Dada-ist randomly unusual behaviour, but this is another symptom of control freakery... impose organisation on the profoundly disorganised