The best suited part for this source only application would be CYPD3175-24LQXQ (footprint same as CYPD3171) which does not have dead battery termination and therefore will not succumb to such scenarios.
We still need CYPD3171 since we want to leave option for power going both ways. Unless you are implying that we can have bidirectional power with CYPD3175?
After some experimentation, I've determined a solution, which is apply a soft reset in the firmware after power goes back to 5V. I keep monitoring the voltage to see when the power disruption is over.