I am citing past comments to demonstrate the individual has a pattern of disregarding basic hygiene measures. And that it's related to their current view on vaccines

And as you can see from their reply they don't mind talking about it.

The phrase "disregarding basic hygiene measures" is also a rhetorical interpretation that indicates you're more interested in battle than curious conversation.

And just because somebody doesn't complain about you digging up old comments, it doesn't make it OK to do. We can't know in advance how it will make someone feel, nor how they actually feel about it, even if they haven't complained about it.

The central issue is still that you seem to be using HN primarily for ideological battle, which is not what it is for.