The claim was that people were motivated to argue by the ease of the target rather than by the genuine threat of harm. In the case of anti-vax, I don't agree. I think people see a threat to their kids and react accordingly.
Anti-vaxxers are only a threat to kids who have another health condition that prevents them from being vaxinated. So, in most cases, it's a threat to somebody else's kids (who isn't even present in the conversation) not a threat to the anti-anti-vaxxer's kids.
This is not true. Vaccinations are not 100% effective. They're usually in the range of 90% to 99% effective. Protection also wanes over time. Because of this, herd immunity protects everyone, not just those who are unable to be vaccinated for health reasons.
