I can see, and think I could argue, both sides of the issue. The question I would pose is how does selling edited copies of a movie negatively affect those who want to see the regular version? In other words, if there is a copy of Schindler's List, without all of the nudity, how does that affect my watching the original version? I can't think of how I'm hurt if somebody else is watching an edited version.
If I buy a CD, I might listen to songs out of order. Or I might skip some songs because I don't like them. Why should anybody care how I interact with the 'art' that I purchase. I would be willing to bet that a lot of time is spent on 'ordering' the music.
Of course I tend to allow for even further 'meddling' with artistic things. I think those who take art and alter or 'remix' it can often give us new and sometimes refreshing insight. Has anybody heard the Grey Album? Good stuff, if you're into that kind of thing. Or what about Fat Boy Slim? Find “Brimful of Asha” regular version, and then listen to Fat Boy Slim's version. I'm sure some might prefer the original, but it was Slim's version that shot the song to the top of the charts. Slim is an example of somebody who takes artists' work, fiddles around with it, and gives it a new twist.
Of course this isn't what Clean Flix is doing, they are just 'sanitizing it'. But I guess I tend to be more open to people taking existing material, remixing it, and allowing others to experience it in a different way. If people want to watch a movie without any of the violence or the nudity, let them do it. It doesn't affect my experience.
Maybe tomorrow I'll argue the flip side of the issue, and call myself a friggin' moron.