Yes, the particle event continues to be executed (as confirmed by my tests seen above - admittedly, it's a terrible wall of text). They are moved as well, or stuff like p.gravity is considered still.

Somehow their lifespan is set to "range unsigned var" under some circumstances. This depends on the camera's position (and the particle's world position, presumably), meaning moving the camera affects it (on screen or alternatively you have to be very far away for lifespan to not be set to that huge value). Weird!

EDIT: Seems like the var range is +-2097152 after all and not 1048576, right? var is 22+10, 22 bits for the mantissa (?), 21^2 = 2097152.
DEBUG_VAR on a fast increasing var confirms.