I have an abiding soft spot for Zappa. I had a big enough Zappa phase as a teen that I actually had a poster of Zappa, sitting on the toilet, in my room at uni. Got me laid a lot, that did.
Nowadays it's mostly about liking the guitar soloes, which is almost certainly not the thing about Zappa Ben Watson likes.
But, I dunno, Zappa was just very emphatically his slightly grotesque self, would not be persuaded by anything or anyone to tone it down. Horrible, arrogant, self-regard - maybe. But I also take it as fighting one's corner, demanding that there be a place in the world for something as misshapen as oneself, to the point of spamming the world with as much of oneself - meticulously archived, every live show taped and indexed - as one possibly can.
I like that Ruth Underwood (the Mothers' fantastic xylophone player) remembers him with great affection and gratitude. He was often shitty about women, and sometimes a shit to them, but he always made room for fellow-travellers whoever they might be.