Loosing vast amounts of historical posts or would I say "cultural heritage" is a shame but I couldn't trust the party hosting it ...
So with Twitter I did the same, 13 years of tweets. Even took a one month payment on a bulk erase / unlike / unfollow / unretweet service to get it done in a reasonable amount of time.
I think he meant save the actual notes themselves. Often necessary for sync engines to replicate the notes to other devices and manage version control.