I know someone who abandoned the Blood Type Diet because they thought too much of it was a matter of faith . . . with so much of it being based on long-term effects. Soy is possibly that way for many As. It gets questioned regularly by As on different forums, but Dr. D. continues to say it is okay in all forms.
In any event, tempeh can substitute for tofu (except silken) in many recipes. (I don't even know the name of the brand I use; there is only one at my Whole Food, so I never took note.) Rice/almond or other milks can substitute for soy. Cheese is the big problem . . . though sheep's/goat's is neutral.