It doesnt matter if you get RDM'd in the first place, you cannot make a rulebreak just because someone else makes a rulebreak. You still RDM. You are at a very remote house and only there to provoke them. Read General Rules for Provoking and GR6.15 for RDM. From what it seems they also did RDM to you, situation is not 100% clear, but you can report them for it in another section. The punishment is still correct, since you do Mass-RDM because they RDM - thats still not allowed.
They were not punished because when I arrived to the ticket, they were all already dead while you still killed everybody unrelated to the situation coming out of the house. We can only punish what we spectate.