radix.
Unless the surges were so severe that it had an effect on other parts of the motor causing the flame to reach the liquid fuel it doesn't explain what happened.
Surges can become quite severe, as the quote earlier in this thread about the Saturn 5 surges demonstrates. Pushing the quoted 68g lateral surge acceleration though an airframe, is likely to cause damage.
It is not at all clear that this is the problem here, but surging was mentioned as a problem on previous flights, even when using the rubber fuel.