''Without the pull-up or pull-down in place of the battery it WILL fail. If you read the data sheet it discusses how it stops processing I2C commands when vcc transitions below VBat. Interestingly it is the transition that is the key. Pulling Vbat low prevents this protection logic from disabling the logic.''
This is coming from a ''Super Member'' on the Microchip forum so that is
good enough to try a pulldown resistor on the + of the battery holder.
10K may not be the best value but it will not destroy anything if it does not work.