Don’t worry about the first item. It was a theory about the issue that has of now not been proven to to the cause of the issue. So, just ignore it.
If you put power on the I/O pins before the PMIC powers up and reset is released, you can blow up the processor. So, don’t do that. Gating means that you should not allow your circuitry to drive the pins before reset is released. That means you add circuitry that disables your circuitry from driving the pins. You turn them off. You run them through a gate (buffer) that keeps the signal tri-stated or turned off.