Remove reliable friend mutation from single player servers

[PlumbusFungi]

I had been trying forever to figure out what that final mutation is that I haven't unlocked. Finally, I just looked it up, and I am super disappointed that I will never unlock it because I am playing single player. I really think that the reliable friend mutation should only be available on multiplayer servers because there literally no chance of ever achieving a mutation that requires you to revive friends if you are playing by yourself. Just leaves that "I didn't do everything I could" feeling, ya know? Unless I am totally missing something here? Suggestions welcomed..