Because Click-to-Run (a/k/a virtualized) is not the normal distribution method for Office software, I'm not at all confident that "Microsoft would use the usual tool" to distribute a future update to it.
My gut tells me that we're seeing side-effects of New And Different distribution method(s) for click-to-run (virtualized) software..
Actually, with Office 365/2013 CTR IS the "normal", actually almost 99% ONLY, distribution method for Office!
CTR is the "only" distribution method for 2010 Starter.
CTR started to be the "normal" distribution for online downloads of Office 2010 ...
It is this sort of issue that continues to confirm my personal contention that CTR is STILL not ready for the average consumer. CTR is not appropriate for "home' users because it assumes a constant "high speed" internet connection (OK, at least once a month).
But there are still many, a majority?, of users who do not meet that simple fundamental assumption for the running of CTR versions of Office.