Process is in part a matter of timing, a new Californian proposition 8 can be introduced can't it? And then if that's the case approximately 20 or so States legalisations could be overturned ultimately from this decision? If Kennedy was willing to overturn all these then why now? He had an option to do so with an injunction (as you mentioned above) but didn't do so, to me that seems to suggest something.

Also is Kennedy the only swing voter? I thought Roberts was also less predictable (while the other seven you can probably predict confidently).