"With enough force I suppose it backs itself out, punches into the lockring, and because the lockring spins the opposite direction, it just pushes the lock ring out and takes the threads with it."

Say that again?

First, that would require a ton of torque. I'm sure someone could do the math but 2000 ft lbs might do it. But frankly, I'm not sure you predict the correct result from that much force. I think the locking would not move - that the cog would strip its hub-threads. Or maybe the hub would blow out the spoke holes. Or maybe the pedal spindle would go first? Perhaps the chain stays would crumple. Or the chain would break.

Thread hijack - what's the weak point in this mechanical transaction. Assuming someone's going forward on a bicycle and can exert enough reverse force on the pedals to make something break. What breaks? Let's assume that the bicycle can't skid and can't go backwards.