It is something that I've thought about - the contradiction between privacy and the need to communicate yourself to the generations to come and the broadcast into the void it requires. If your friend is okay with his privacy in the archives, he might be glad to know that in hundred years, there will be an AI whose PHD will be on the emotional significance of new technologies in the lives of early adopters of the Internet, the case of user John Smith 1988.

Yes Usenet used to gave a spool lifetime, but that was clearly variable and there were no guarantees about it. Anybody could set up a mirror and frequently did. Also anyone could copy out content to other media and there was no expectation that they couldn’t do that.

We are all responsible for what we post to other people and in some cases also the effect it has on them. Consider bullying, abuse, criminal conspiracy, the record of receiving a message belongs to the receiver not the sender.

connect with people and work through some pretty heavy emotional challenges

is a goodmine and insight into history.

I don't think we give a lot of weight to what the original publishing intent was for anything published 100, 200 years ago, why would the change in the future?

Without publishing it rather becomes tomb raiding even after thousands of years