That’s technically correct but in practice it’s about as accurate as, say, assuming that you shouldn’t own anything expensive because it’s possible for anything to be stolen.
In real life, there are not billions of Mallorys watching your stuff constantly. Most people are decent and most of the others are deterred by laws, and the number of people who are willing to help abusers is relatively small.
Just using some real-life examples, think about doxxing or revenge porn. It’s technically true that this data cannot provably be removed from the internet but in practice most people didn’t save it and the ones who did became a lot more covert once the legal system caught up, which means that in practice far fewer people see it. The initial damage may have been done but that doesn’t mean we should give up and do nothing because there isn’t a theoretically-perfect option.
Sure. But if I e.g. accidentally uploaded something sensitive to GitHub (that can’t simply be changed to a new secret), I’d certainly delete it in a hurry, rather than shrug and say ”oh well It’s on the someone has already copied it so I’ll leave it”.
But in that case, are you saying you _wouldn't_ immediately change the credential you committed? Sure, the possibility of an adversary forking your repo after that commit but before your revision is small, but still exists.
Once a secret is exposed to the internet, it should be considered public and rotated. In this case mutability/immutability is moot though likely there are applications for other, non-credential secrets that are not so easily rotated (like your home address or something).
