Does arm stay mode disable motion detectors?

Yes, it does!

Stay mode is an arming setting that activates all of your perimeter zones, but not the interior zones such as motion detectors. This setting should be used when you wish to arm your Honeywell alarm system and still be able to move around your property without setting off any motion detectors. When your alarm control panel is armed in stay mode, the motion detectors will not be active. If you armed the system in away mode, all of the sensors including the motion detectors would be active, and you will set off the alarm if you move around inside the property.