Had never heard of garlic scape pesto till now! I will unquestionably be doing this in the Summer now that I know. Last year we just put the scapes in the salads and the children wouldn't eat them. So, thank you for this great tip.
I considered dairy as the source of the problem. He doesn't drink milk and always says he doesn't like cheese or butter, but in reality he does still have a bit of cheese and butter in some of the cooked foods Sabrina likes to make. This would be my first thing to exclude if we were going to exclude anything.