There are some great veggie dishes which hopefully would be palatable
for your son, that is if he loves his veggies and you're not having to make do with pizzas etc
There are great bean dishes, fassolakia and fassolias, giganites, all different types of beans in tomatoe sauce, just make sure there aren't any meat balls swimming around in there as that is a traditional dish that goes together
horis kreas means without meat, might be a helpful phrase
Also there was a great caulifower dish in the same tomato based sauce, not sure if cauliflower is good for him, my sons run a mile from it at the moment!
also briam is potatoes with zuccini and tomates
if you find a good traditional taverna you should be able to find a selection of these dishes.
also stuffed tomatoes and peppers are sometimes without meat, I am not sure how corfu is re vegetarians but know on other islands have lived on like Crete in the small villages it is look upon as really strange not to eat meat!
I think it stems back from the post war era when to eat meat was a sign of wealth and oppulance, or at least meant you could pay the butchers bill!
if you have any questions PM me or post here!