And if Red Hat does get nasty, anyhow?

A decision to withhold source in this way is likely to have an extremely detrimental effect Red Hat's ability to retain some key, high level kernel developers such as Alan Cox, Stephen Tweedie and David Miller.  In their position, I would be watching my employer extremely carefully given this latest move.  Red Hat developers know that they need to make money as a company, but I believe (economy permitting) the company would experience a mass exodus of some of it's key developers should it so completely violate the spirit of free software.  They've already taken a step in maddening direction for many.  I'm sure that executives are well aware of the fine line they now walk.