The PRV will be there to protect the hydraulic system from over-pressure - not as a fail safe for avoiding RBS.
AnFI - excessive torsional force is exactly what you get when you force a blade to go somewhere it doesn't want to be - ie at high AoA - they just got the maths wrong when they estimated how powerful the jacks needed to be to control that force - simple under-engineering.
Why do you think the bigger and heavier R44 has hydraulic boost where the R22 doesn't?
More powerful engine equals higher AUM and/or smaller disc equals higher disc loading equals higher aerodynamic backloads equals more powerful control systems.