P2 VBAT_MEAS pin voltage tolerance

Can voltage on the VBAT_MEAS pin safely exceed 5V if it's not being read?

The recommended maximum is 5V. It works like a voltage divider in front of a 3.3V ADC, so there's some tolerance to go slightly above 5V before damage occurs, but it's not intended to be used above 5V. This is true whether you're actually measuring at the time or not.