There isn't a setting but if you control the light directly it will disable the nightlight for 12 hours. Playing around with the driver I see that if you change the hue it changes but doesn't turn on the light, The next time you turn it on it is at the new hue.
So I just setup a simple rule to test if this is enough to keep it from activating.
It runs three times a day. Samples the current hue and tells the device to set that hue. This way if it is on it won't change color. Two things: I don't know if just setting the hue is enough to keep it from going back to auto mode. Even if that works I don't know if setting it to the current value will work.
At this point I won't know until tomorrow if it works. I suppose a good test would be to leave the rule off and wait for it to go into auto mode. Then wait for the light to turn off, set the hue in the driver, and then trigger the motion sensor. I think I'll left the rule off for now and wait for the light to reset and do the manual test.