Adaptive here means whether necrophilia occurs in order to still produce offspring, i.e. it’s ‘conscious’ (I use that term veeeery loosely here) or if it occurs just because the animals don’t recognize that the partner is dead.
I remember a paper about a frog species (not sure if it was the one from the meme) where the males participated in necrophilia, but they basically tried to squeeze eggs out of anything they grabbed. Living female, dead female, stone, sponge. All the same.