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.
Yeah, that’s exactly right.
As for the second part, I’m not sure how to answer. Squeezing the partner is without a doubt adaptive, but squeezing anything that is roughly the same shape is a byproduct with no (strong) evolutionary pressure. Now, the question is whether functional necrophilia is adaptive or just a byproduct is very difficult to answer, but I lean towards byproduct.