I wonder if that's an innate response for when newborn monkeys aren't breathing/fluid in lungs. I'll bet a zookeeper would know. Maybe baby monkeys routinely fall into the water and have to be hauled out by momma
and pounded on the back, and that monkey thought that immersion was a necessary step in the revival ritual.
Maybe that monkey just started a new monkey religion of baptizing deceased monkeys to bring them back to life