If anyone is curious about our "legal backing" for preventing these types of deletions, here's the administrative answer. Each page had some text in the footer that reads:
USER CONTRIBUTIONS LICENSED UNDER CC BY-SA 3.0 WITH ATTRIBUTION REQUIRED
This goes for all questions, answers, comments. It was not the case for this question, but as a general rule if a user insists that it's "their question" and they can delete it if they please, they're likely misguided. By posting under CC BY-SA 3.0, you immediately surrender the right to control its publication.
Here's the boilerplate message that moderators have the option of sending to users in this type of situation:
You have recently removed or defaced a lot of content from your posts.
Please note that once you post a question or answer to this site,
those posts become part of the collective efforts of others who have
also contributed to that content, and should not be removed except
under extraordinary circumstances. Even if the post is no longer
useful to the original author, that information is still beneficial to
others who may run into similar problems in the future.