My comment wasn’t meant to dismiss your point. Only to confirm that fungibility is a function of those of us that use and accept bitcoin. If a government bans a particular “batch” I don’t care. I will still treat them the same. If enough individuals behave the same, the government ban becomes useless. So what you are describing is possible, but only if bitcoin’s user base allows it to become so.

I, for one, will not. Others may do as they see fit.

Plus, the amount of Bitcoin that either one of us owns doesn’t matter to me.