That depends. In this case it's good actionable advice that should hopefully lower cognitive load. Politely suggest a fork, then if the nagging persists block and move on. Sure if you're in a position of authority you have a responsibility to the community but cutting ties with a stranger who is flagrantly violating social norms is perfectly acceptable. There's no expectation that you indefinitely burden yourself with their poor behavior.
Sometimes dropping the ban hammer really is in the best interests of both yourself and the project.
Relying on maintainers to always do the right thing to ensure our security by telling them what to do is not the way.
They're not useless. They just don't work on the individual level but on the collective. It's a numbers game …
The advice is actionable because it is a concrete change that could be made. I believe it to be relevant to the context because someone in a position of authority who is badgered into accepting something would most likely benefit from reevaluating how he is interacting with the general public.
A lot of people don't want to be responsible for that. It's not fun to carry that weight.