Do we want to allow questions that are about a one time event, which will presumably be completely useless to everyone in a month or two when the event is over?
Answer without addressing the usefulness of Q&A about one time events that, will be solved soon. I believe you have underestimated this particular event.
Original (Feb 2017} "This road closure is anticipated to last several days, as road crews assess and repair the road." It is now several months into closure without an estimated completion date given. There is only a single route left, which is subject to the same potential for loss of use. The potential for future similar events remain.
This is a major event, effecting a major national park, it has current and historical significance.
I personally don't think that it should be a major issue. On TGO we have 3,505 questions so far and I don't think adding one to it is an issue, unless its not directly suited.
While I do agree about your concern on allowing a question which might go obsolete after a deterministic span, I think few of us including the OP can flag the question for moderators to get rid of it after it is no longer applicable.
The only intention I have to do it this way is to attract web community (users) who specifically are looking for information about this particular event.
In old SE speak, that is the definition of a question that is too localized. A slight modification to the question would improve it in my mind. Specifically, asking where else to call besides the concierge desk at a hotel about road closures in Yosemite NP would be a great question. A great answer would demonstrate the usefulness of the suggested method by providing details about the current situation.