It’s discussed in the Reddit comments, if you want more details, but briefly: A rare species with a long life might leave on the order of ~100 dead a year. If each corpse has, say 1e-5 chance (low but still plausible number) of being found by a person, then it could take a while.
I don’t know of any claim that they would take care of their dead, but I don’t see that as implausible.
It’s discussed in the Reddit comments, if you want more details, but briefly: A rare species with a long life might leave on the order of ~100 dead a year. If each corpse has, say 1e-5 chance (low but still plausible number) of being found by a person, then it could take a while.
I don’t know of any claim that they would take care of their dead, but I don’t see that as implausible.