Is there any reason, out of story, that RH needed to die with no afterlife for him? I understand it happening to Hades, but they could have killed RH by a blast of magic or pushing him out the window or something that gives the character final rest and peace for eternity, not….nothingness.
I suspect it’s because A and E don’t ever want to revisit Robin or be constantly plagued about seeing him again. They get that all the time with Nealfire. This way, with Robin, he’s literally obliterated and there’s no chance of going to the Underworld to get him, no magical handwave to bring him back. He’s gone for good.
Survived only by his son Roland who will be raised by the Merry Men, and Baby Robyn who will never know her father or her brother because they live in different realms.
"If you go as far as you can see...you will then see enough to go even further." - Finn Balor