From what he wrote, rejecting mayo is not due to his vegetarian choice, but because of the texture of the food; which is not unusual.
jaderis writes:
For example, I am physically disgusted by most milky or creamy food stuffs (i.e. mayonaise, cream cheese, cottage cheese, sour cream, whipped cream, yogurt - it's a texture thing mostly)
His point in
Message 12 being that laws should be based on reason and not personal disgust.
What point are you trying to make with your observation that concerns the topic?
"Peshat is what I say and derash is what you say." --Nehama Leibowitz