The way this sounds is that you are more concerned about politics as in people who take party positions and may feel excluded as a group when the majority of the community takes a different position. This is a slightly different issue i.e. party politics, and I think it is fine/a good thing, but it is also important to distinguish the two. This should essentially be under the same umbrella as personal attacks, as they are essentially the same thing.
I see this great move as a way of the community lifting its head out of a sandy quagmire to glance at the shining beacon, the vision on the hill, the where we want to be, unsullied by political nausea. Sure, in a week we can get back into the grim reality, the tech-noir crapsack future, but perhaps for one week we can focus on a positive future and its soaring aspirations. Go Dang!
I don't think politics have overtaken the site or even become a significant part of it, so I wonder why politics-averse individuals cant just avoid political threads?
HN is a community for the the intellectually curious, who come here for a wide range of interests (some of which have political aspects, of course--there's no getting away from that). But there's a different kind of users, ideologically committed ones, who use HN primarily for political battle. That's not something that sits well with the purpose of this site, as I tried to explain above.
Those users really want a different kind of site than HN, and need to find another, or maybe start a new one. Plenty of new sites have spawned from HN; that's partly a function of our not trying to be all things. HN has always been in the lucky position of not needing to grow for growth's sake, so we're happy when people who want a different kind of community find it, or create it.
(It's interesting how the "this is just for a week" thing hasn't seemed to enter the conversation.)
On the other hand, the idea of an interminable ban on political discussion has many obviously salient implications, emotions, and such. A sort of half-baked analogy is that it's like lighting a tiny, contained trashcan fire in the middle of a nuclear reactor--it's not really a big deal but it's easy to see how it could trigger high-magnitude reactions from onlookers.