To me it reads veganism in the form that the individual practicing it does not deviate from it, nothing about telling others how to eat. How is the existence of those people counterproductive to people eating less meat?
"Veganism in the form of religion that thou must not deviate from" is entirely counterproductive because it tries to get people to completely stop eating meat. Large majority of the population doesn't want that so they continue with the same meat consumption, while we could eat less meat that we currently do without giving up on some BBQ/steaks here and there.
It creates a false dichotomy, putting people on the defensive because they don't want to give up meat.