I have no insider info, this is just what I think.

The Linux desktop is Red Hat's complement in the sense of commoditizing their complement. They don't actually care about it as such, but it needs to exist and they want it to be dirt cheap and highly available so it will drive customers to the products they do care about. Without it, they're just selling a grab bag of server/CLI/web-based tools that require a fleet of Windows or Mac desktops to manage, a very different value proposition to being a complete IT solution.