I think very poorly of this year's committee, so I wouldn't put anything past them. But if the answer is laziness, it's a new depth I hadn't even considered. Like you said, the rankings are supposed to be fluid, they've had several opportunities to change it, and now it's at the point where correcting it can't really be justified.
For the record, I've commented several times on how weird it is that the committee has seemed to think the lowest of UW among the undefeated teams, but Oregon the highest of the 1 loss teams (considering their quality loss to UW was all they really had beyond blowing out teams who weren't, or ended up unranked). As I mentioned earlier, this group seems to use what if and could have been justifications more than relying on the posted criteria and results. So who knows.
Whatever the case, they've for sure got themselves in a situation where they might have to do something that's going to be really hard to justify.
What if this scenario except Washington wins? Do they take Alabama or Texas?