I completely understand the use-case of why you have this question.
Unfortunately, any update in the form of additional content that is not an 'edit' (i.e. - initial post or reply) will follow the standard procedure of triggering a notification to those who have subscribed. There is no 'suspend notifications' feature that I am aware of for the Admin...or not one that does not at least permanently remove the subscription for all users).
However, Khoros could (in theory) suspend notifications, or perhaps even delete subscriptions and then re-instate them, during the window that you would want this done (hopefully would not be more than a few hours). This would probably require some kind of script to be created, and would also require some good cooperation / timing (and all this could get even more complicated if you have a huge Community).
What I would recommend is that you open a Support ticket, outline what you mentioned here, and ask what the Level of Effort (LOE) would be to get such a thing done. It would be a custom Professional Service for sure, but wanting to have a non-intrusive Customer Experience whilst simultaneously updating all of that content might be worth the expense.
Please do let us know what comes of this (not all of the gory details, of course), because I am very curious if a customization like this is possible. And ultimately, I am curious as to how it will / does improve your Community.
