My guess is that [Tycho] is ultimately the person with the most control over the final say, and he is choosing to not act at this point. If he changes his mind, this will probably be a done deal.
Somewhat true. The developers can decide to make whatever changes that they want, but if the majority of the miners do not support the changes, then it doesn't matter much what the developers actually want. So it really comes down to convincing enough pool owners and miners that the change is worthwhile. However tech savvy the miners may be, they are not all developers themselves, and dissent among the development team seeds confusion among the miners. Tycho's insistence for more time, in light of some dissent, is a wise man's opinion. I, for one, don't know enough about programming to even know what I'm looking at, so I (personally) have to trust someone. I favor Gavin because he was knighted by Satoshi long ago, for good or bad. It's entirely possible that I'm in error doing so, but if this is really a near-term security issue, then something must change and Gavin is (IMHO) the commander of necessary changes. Even if a near term bug fix isn't forthcoming, a checkpoint update every few days would be prudent. Of course, that means that we would need someone qualified to actually monitor the blockchain with human eyes to make sure that there have been no attempts to capitalize on this bug before releasing the next checkpoint upgrade, but at least then it won't be required that everyone participate, since if there is an attack that screws up the blockchain, a valid copy of it will still exist somewhere on the network that will allow us to contain damage.