PP, you are naive to think that anything you post on a public forum or profile doesn’t have the potential of being archived, whether it is done by the owner or anyone else who can see it.
I have a feeling the White House also archives letters it receives via ye olden pony express and has been doing so for hundreds of years. How is this any different? I don’t recall them notifying anyone that they’ll be archiving any mail they receive, but I guarantee you that they do. Generally when you send someone something, it is implied that they will keep it.