It is not the G level that is causing the issue. Turbine rub (and subsequent damage) is primarily caused by the gyroscopic forces induced by very high Pitch Rates and/ or Yaw Rates.
Remember how hard it is to rotate a spinning bicycle wheel, or when playing with a gyroscope - our rotating turbine components are exactly the same, but ours are now spinning at 100,000rpm or more.
The gyroscopic forces generated by these pitch/ yaw rates are huge, and are transmitted through the bearings and into the case. With both the compressor and turbine wheels hanging off the end of the shaft, and only supported by the two bearings, they will naturally deflect, to include gyroscopic precession, and may start to rub.
Rubbing at 12/6 o'clock is signs of too much yaw rate, and rubbing at 3/9 o'clock is due to too much pitch rate. Precession effects show up 90degrees away from the applied rotation rate.
If you don't get rubbing and/ or catastrophic failure, you'd at least have to expect not to make the full 25hr bearing life.
There's been more than 1 full-size engine that has had major rub issues by flexing of the rotating parts due to gyroscopic forces. Leading to multiple aircraft losses and loss of life too. And they were designed top handle it too.
Our model engines survive this abuse more by luck than design.
Paul