much of the Bible is not systematically evil but just plain weird, as you would expect of a chaotically cobbled-together anthology of disjointed docu… - Richard Dawkins

To be fair, much of the Bible is not systematically evil but just plain weird, as you would expect of a chaotically cobbled-together anthology of disjointed documents, composed, revised, translated, distorted and 'improved' by hundreds of anonymous authors, editors and copyists, unknown to us and mostly unknown to each other, spanning nine centuries

I can think of no moral objection to eating human road kills except for the ones that you mentioned like 'what would the relatives think about it?' and 'would the person themselves have wanted it to happen?', but I do worry a bit about slippery slopes; possibly a little bit more than you do. There are barriers that we have set up in our minds and certainly the barrier between Homo sapiens and any other species is an artificial barrier in the sense that its a kind of 'accident' that the evolutionary intermediates happen to be extinct. Never the less it exists and natural barriers that are there can be useful for preventing slippery slopes and therefore I think I can see an objection to breaching such a barrier because you are then in a weaker position to stop people going further. Another example might be suppose you take the argument in favour of abortion up until the baby was one year old, if a baby was one year old and turned out to have some horrible incurable disease that meant it was going to die in agony in later life, what about infanticide? Strictly morally I can see no objection to that at all, I would be in favour of infanticide but I think i would worry about/I think I would wish at least to give consideration to the person who says 'where does it end?'

Undisguised clarity is easily mistaken for arrogance.

When you plant a fertile meme in my mind you literally parasitize my brain, turning it into a vehicle for the meme's propagation in just the way that a virus may parasitize the genetic mechanism of a host cell.