If someone shoots you in the leg or body randomly without downing you or killing you, that is called one way initiation and is not considered RDM. This makes it that if they end up downing/killing you still without any dialogue or proper time to respond then its considered RDM. However during this time you can shoot back because they appear red and you just can. The second you start to shoot back at the player you are all initiated and its no longer 1 way.
Nobody cares bud, maybe next time go get some extra clarification from the admin before throwing a little tantrum like a baby you stupid little moron.