Content is mirrored on all federated instances and it is very rare for an instance to shut down without notice.
I meant that it’s not directly associated with you as the owner through your migrated account.
Edited comment (many to some).
I don’t think that’s even desirable and also legally questionable. But anyways, these posts are not gone with an instance shutting down and thus I don’t really see a problem. You can always add a link to a mirrow of those old posts in your profile.
thus I don’t really see a problem
Except you no longer can edit, delete, etc. the posts.
You’ve lost complete control over your data, and there’s no way to get it back if your instance vanishes.