The valid input range really only applies to normal operation, of course the
input voltage can fall below 1.65V but them the device will not operate
correctly if at all.
When Vout exceeds Vin by more than about 75mV the device turns off the switch.
As long at the input or output voltage is within the normal range the reverse
current protection circuitry will activate. If the input or output voltage is
less than 1V, the internal diode anode will be connected to output and the
cathode to the input.