We already have newbie warning flags, which only need support from a single DT2 (of which there are plenty), to display a similar such warning at the top of threads. I don't think a "bullshit warning" would necessarily be that different.

Not that I'm arguing for a demerit option (I'm not), just playing devil's advocate. A demerit button, despite all your caveats about carefully selecting a small number of users, would invariably be used at some point for differences of opinion. Just as I have never agreed with red tagging trolls or altcoin shills, using a demerit option for this reason would be inappropriate in my view. While I wouldn't necessarily object to it being used against posts which are flat out factually wrong (I mean, read the second post I linked to above - it is utterly meaningless), just like with scams, it would be impossible to enforce this fairly and impartially.

I actually reported the post I referred to above, not because it is wrong (now that would be censorship), but since the code is largely plagiarized (for example: https://www.c-sharpcorner.com/article/compute-sha256-hash-in-c-sharp/), and there is exactly zero chance a user with such a complete lack of understanding of what a hash even is could have written it, but the report has been left unhandled.

There isn't, other than to do what has already been said - correct their nonsense and don't merit them.