They "should" update when appropriate, but I would assume the biggest reason they aren't offering cpanel with RH9 is due to some bugs and problems with newer versions of RH and it's inability to play nice with some software. There are people running RH9 + cpanel.. but there are more running that setup with problems.
So I'm guessing they are saving themselves a lot of support hassles by not offering it until it is near 100% stable.
