That Mad Greek menu is barely veggie-friendly. If you're a strict vegan/vegetarian, you're not going to be driving 10 miles for two options (Greek salad and hummus with pita; questionable on the vegan pizza, unless they have a separate grill) that you could get in your own town. All the other dishes at Mad Greek can only be made vegan by removing items, which is fine in an emergency but not exactly geared to vegans. (I just hope the murderer enjoys nothing but peanut butter every day for the rest of his life.)
Why not falafel and dolmas? With some hummus? The standard thing that vegans order at Greek restaurants and why Greek restaurants are usually considered vegan friendly.
Also, many places these days prepare Greek rice with vegetable broth or will do so on request.
Now the separate grill thing is an issue, but separate small pans for vegan preparation of falafel are already standard most places (who would use anything other than a falafel pan to fry falafel? or a special falafel deep frier - because otherwise, the falafel are not gonna taste right).
Vegans are very accustomed to ordering things with ingredients subtracted (as are vegetarians) and cooks are extremely accommodating and used to it. Most restaurants do not have yummy proteins like hummus and falafel though. And dolmas. All Greek restaurants have great salads, IMO, and is it really a big deal to ask for no feta? Millions of people have food intolerances and do this daily.
Pizza may go directly on the oven rack (but that assumes he can eat yeast, in his extreme vegan state), Don't know how he feels about oven racks and don't care - he's going to end up being fed by a tube if he rejects the vessels and ovens in which his jail food is prepared.
Regular pizza places are much worse, because vegan cheese (IMO) is not that great. Rather have a traditional food like refried beans (almost always vegan where I live and travel) or falafel. In this case, I do wonder if BK regards yeast as an animal because, if not, then he also gets pita bread.
You're right though - he's unlikely to get any of this great food in jail. Peanut butter it shall be. With celery. With apples. And, if he's okay with yeast, he can have a PBJ sandwich.