A question can change during the time between when you first write an answer and when you submit it. Or another answer can be posted that covers the same idea, or that covers a different idea that sounds the same (so your answer wouldn't make sense without edits to clarify the difference). And what if the OP does find the answer and post it? Do you still want your automatic answer posted? What if the OP's answer is not really an answer, but they are using the system incorrectly and posting what should be a comment or edit as an answer (as frequently happens). Or what if they don't post an answer, but instead provide the solution as an edit or comment (as frequently happens). There are far too many situations where the behavior of the feature you're suggesting would be seriously, sometimes even harmfully, wrong.
Without those factors, an "automatic answer embargo" is unnecessary--if going back to submit an answer disrupts your workflow, you can change your organizational scheme, or you can avoid writing the answer until you want to post it. Even without considering its disadvantages, it's unlikely it would make sense for developers to put in the necessary effort to design and implement this feature.
With those factors, posting answers automatically after a time delay is undesirable, and would produce enormous confusion on the part of askers, answer authors, and others. The presence of this feature, in the form you're requesting it, would be an outright bug. A possible fix to the bug would be for you to be prompted to review whatever changes have been made, before giving the answer. That would have no advantage over the current way; it would interrupt your workflow just as much if not more. Another possible fix would be for the answer only to be posted if no edits, comments, or answers have been posted since the "embargo" was scheduled. Then, often your answer would not be posted. So you'd have to check back to see if it were posted and post it manually some of the time, since there's no way to avoid posting it when it shouldn't be posted, but still post it whenever it should be. That would also interrupt your workflow.
As a secondary consideration, the question might be closed, as a duplicate or otherwise. It's unclear what the most appropriate behavior would be for this feature, when that occurs.