Olives are a fruit and yet they are disfavored by the movement. Coconuts are a seed but they are considered acceptable. And within seeds, maíz, soy, and safflower are all very different botanically.
Coconuts are fruit, actually. Also while corn kernels and soy beans are technically seeds, they are, at least in my opinion, pretty far from the vernacular definition of seed. Part of this is that soy is a legume, corn a cereal, unlike safflower and rapeseed, which might matter nutritionally.