People still have trouble wrapping their heads around the fact that same-gender attraction (at least in humans) is about more than sex.

... and in the lifelong pair-bonded geese who were the major first example in TFA.

I don't think that's the claim. I think the claim is that what typically call homosexuality involves pair bonding and sex.

That's not always the case. Personally, I lean toward bisexual homoromantic. This kind of split attraction is probably more common than it seems, but we didn't have language or a concept for it until recently. I know several people who are asexual and have various romantic orientations.