Being vegan or having any personal requirements when you put yourself out to the public, you must understand it is YOU not the guest who is outside the norms. This is definitely not a bad thing as I admire people who have strong convictions. Again, you have a business and you are choosing to market on a general booking platform for the general population.
Perhaps, you need not to think you are being unfriendly, but you have a unique opportunity to market to like minded guests. I would think someone like @Kath9 might be attracted to a home that is just like yours.
Celebrate your perspective and invite others to do the same, but do not blame the guest who is not reading or remembering every detail in your description. How about your welcome message includes, "We are strict vegans and would love to celebrate that perspective with you, but if you prefer to eat meat, we ask that you limit use of our kitchen..." Not unfriendly, but informative.