Can rigor mortis be broken with a 'tug'?

Answer 1

No, but you can break bones like that. You pretty much need to wait till it wears off.

Answer 2

Rigor morits occurs because the body is no longer capable of generating ATP for the respective myofilaments involved in muscle contraction. ATP allows these myofilaments to return to their resting (or in this case...eternal resting) state. In its absence, rigor mortis wears off only after the myofilaments degrade sufficiently, thus releasing the tension.