Unfortunately, when you post ANYTHING online... one must assume it's like a tattoo... that is to say permanent. Not saying it's right or wrong (because believe me I have my own privacy/trust issues), just saying it is reality.
It isn't reality. Reality is that it's simply data on a server. Data on a server isn't permanent, the web was never designed or intended to provide an immutable record of anything.
Data is only saved when it has value, and only as long as that value exceeds the cost of maintaining continuous copies, and sometimes (as recently nearly happened with Google code) people simply become careless and the one and only copy of something vanishes without a trace. Many, many things have vanished from the internet without a trace.
Assume permanent data when you want something deleted and temporary data when you want it saved. If you want it deleted it's probably because someone thinks it is worth saving. If you want it saved, well it doesn't mean anyone does,(or that who ever does will make it accessible) so you'll need to ensure it's paid for.
Undoubtedly, nothing on this planet, whether digital or physical, internet-based or in print, is truly everlasting. Eventually, everything returns to the earth, a poignant reminder of impermanence.
Drawing a parallel to tattoo removal by laser, I'm reminded of an old girlfriend's experience. While she possessed a remarkable pain threshold, it was an ordeal she wouldn't willingly revisit.
So again, I still feel data online is very much LIKE a tattoo in its permanent nature, and time only strengthens that feeling.
If I made an actual article hosted on a site which could be equated to news or magazines of old, I would assume it's permanent since I would assume the same in reality.
If I post something in a discussion forum, I cannot be sure nobody there is recording it and keeping a copy of it indefinitely.
I am however allowed to be upset and possibly persue legal action if the person who did happen to record it now sells it to anyone with enough money or trains an LLM on dictated versions of it.
For the former I believe there is actual legal grounds with damages, for the latter I feel I can choose to never interact with that person again and disparage them publically for what they have done.