I mean, sure. Theoretically.
Same as how "meat is murder" isn't actually an attack, it's just sharing their thoughts on ethics passively on the back of their car.

Realistically, we can probably guess that the person with a lot of "meat is murder" stickers is probably about as likely to be the sort of person to say something shitty to someone eating a burger as this person is to loudly proclaim they eat twice as much meat a day to cancel out a vegan, and that people who are gluten free are just following a fad or attention seekers eating fake bread.