The problem is they have many better time slots for it and for the saturday anime's health.
For example, Fridays were the place for premiering stuff that wasn't their main fare for years. For the longest time, saturday has been for anime. It should stay that way. I mean, the anime industry is suffering big-time because of their move from the sure-fire media of television, to the untamed, unsafe wilds of the internet. [Adult Swim] is one of the last places to have anime on TV.
If anything, this schedule change is probably a mix of trolling the fans, like they have done many times, and a test, to see if they have truly lost the anime-watching audience, giving them one more day to spam KoTH and Family Guy.
At the very least, anime saturdays was a part of [Adult Swim]'s novelty. It was one of the things that set it apart from the other networks. It showed adult-oriented animation, it had absurd and surreal comedy, big things for the college community (their original target), and it had anime, another thing that has been big in the college community. It's just having to see the [Adult Swim] I and many others knew die a little more is just depressing. It's having to see the possible birth of another MTV in our midst that makes me speak here.
Not only that, but anime-watchers usually stick with what they know. The average KoTH/Family Guy watching audience now are the fad-followers. They are the ones that say "ooh, another thing everybody else is watching, let's go there". Once Family Guy loses its clout, they will leave. But as long as they have Bebop, and just anime in general, they will have a dedicated audience.
I know, I know, tl;dr
"I always knew you were no mere mortal... but I had no idea that you were a cat." -Wolfwood
Member of the Senna Fan Club