I would say "worn out" means that thsoe 70Nm match the locking torque of a worn out clutch pack at the real car. As you can imagine those clutch plates just worn out over time, like the clutch between engine and gearbox. rF2 doesnt simulate clutch wear in general, I think LFS did.
I dont know if you're able to adjust preload at the real car from outside, so without dismantling the diff. But for sure you have to, for replacing clutch pack or changing ramp angle (not sure if allowed by rgulations) for example.
Quick google seach gave me this (bit old) Article about LSD's on Porsche Cup (and Street) cars mainly 997:
https://rennlist.com/forums/996-gt2-gt3-forum/494757-faq-limited-slip-differential-lsd.html