Really not too surprising, I suppose, since dyno construction is probably not built to handle abrupt changes since ICE does nit ever have instantaneous response. I'm happy to know these numbers, I was wondering.
It's not the abrupt changes but the torque. There are many ICE cars that will brake awd dyno belts if you tried to dyno them in first gear which essentially is what they're doing with the P85D. That said, the P85D produces a lot of torque. More than Tesla claims.