The slightest asymmetry in the explosions, in time, space or power, will have the effect of applying a minute torque to the spin axis of the system, causing it to precess. Even the tiniest wobble of the axis will be magnified enormously along such a long moment arm between the rocket and the weights, the next detonation to be even farther off-center, eventually causing the cables to tangle hopelessly.

In a linear thrust system, like the Orion axis pulses, a slight error in timing or position or explosive power would just alter the thrust slightly, but would not introduce any rotational instability into the system.