One, this affects the LRP server too, where you shouldn’t be expecting heavy immersion. Beestation literally has a MRP server if you are looking for immersion.
Rape threats were already bannable.
Threatening to murder someone in game is super IC and wouldn’t be stopped by this rule, threatening to murder someone irl would probably already get you banned and should be reported to the police.
As for obscenities, I’m not sure what you’re talking about, racial slurs or just cursing. Both of these could be done IC. Neither of these would be prevented by the IC in OOC rule. I think racial slurs are already banned in MRP, and I would not have a problem with that rule being extended to LRP.
This would be a good fit for the MRP server, but not the LRP one.