What you are describing is not a fanatic. You are describing someone adhering to the basic tenants of their philosophy. A vegan fanatic would refuse to use cash in Australia because it contains tallow, an animal product used as a slipping agent in banknotes.
Guy saw the Satan in the form of a coated almond. It's ridiculous. Twist it, turn it anyway you wish, you're only fooling yourself. It's extremism.
Then there are also the vegan protesters that throw themselves on the roads in front of food trucks. Adhering to their philosophy much? Faith Militants.
People throwing themselves in front of food trucks are fanatics. People casually asking if a food that commonly contains an ingredient their moral code prevents them from eating and then choosing not to eat it are not fanatics.
Nothing about their interaction has any impact on your life, other than maybe making you wait an extra 20 seconds in this particular case.
