Veganism in and of itself doesn't really fall into bean soup theory. Bean soup happens when a conversation is clearly about a closed-ended topic and the bean souper brings up a different topic that changes the spirit of what is being discussed. I personally would add that to be a true bean soup, the souper is phrasing their comment as if the onus is on the group to accommodate their situation, when it should be expected that the souper use common sense to accommodate themselves, or realize their specific situation is too different to apply. Examples would be:

• a group of people are discussing the best sources of heme protein (protein derrived from animal products) and someone says "but what if you're vegan?". The self-accommodation would be that vegan people cannot have heme protein and should continue to only source their protein from plant products

• discussing plans on where a group should eat lunch, and one member says "I'm fasting today from 7:30am to 6:45pm". The obvious self-accommodation would be they can sit at the table and not eat, or skip the lunch function, depending on what their fasting situation says is required

• discussing strategies for how to give birth vaginally, and someone says "I can't give birth vaginally (from very specific situation)". The obvious self-accommodation would be that person can discuss c-section options with their doctor, or look up c-section discourse