I don't follow the logic, are you saying since he is gonna die either way, he might as well kill?
No. I meant the victim is at risk of getting killed after the rape in order to get rid of any evidence.
Previously they didn't bother because murder has a 10x worse penalty.
However if murder and rape both have the same ending then nothing deters them anymore.
If they're sick enough to rape people then they'll likely be unhinged enough to kill them afterwards.
Most likely not all of them will but it will increase the probability that it'll happen.