I'm concerned about what identifying the cult killers as vegan  is doing to the already negative view of vegans.  

I found this in a Farhad Manjoo opinion piece in the NYTimes.

One survey found that vegans are viewed more negatively than atheists and immigrants, and are only slightly more tolerated than drug addicts.

https://www.nytimes.com/2019/08/28/opinion/vegan-food.html

https://vegnews.com/new-york-times-stop-mocking-vegans#:~:text=%E2%80%9CThe%20vegans%20are%20right.,writes%20opinion%20columnist%20Farhad%20Manjoo.&text=In%20a%20recent%20op%2Ded,from%20animal%20products%20all%20along.