light pulsar dragon

ok, so this happened in a duel

i have elemental hero absolute zero faceup
my opponent has red eyes darkness metal dragon and light pulsar dragon. he use red eyes to attack my absolute zero, my absolute zero eff activates, destroying all 2 of his monsters on the field. he has no other dark dragon monsters in his graveyard, and he said he can bring back darkness metal dragon using pulsar's eff. and i said no because the instant that pulsar hit the grave, theres NO dark dragon type monsters and he cant bring back darkness metal because 2 of those monsters hit the grave at the same time, so whos right??

ty for taking ur time to read this, thx

It works because they hit the grave at the same time. Pulsar's effect is optional, though, so you could not activate it more than once in the same chain.

REDMD becomes a target for Light Pulsar because it hits the grave at the same time as Light Pulsar does.

This is a common play for Pulsar.
Your opponent was right. He can bring back REDMD.