Assume that power-manager is disabled. And you use the panel to launch the "power manager settings". A dialog pops up telling you that power-manager is not running and if you like to start it or not... You can answer the buttons with "yes" or "no". If you click no, then power-manager is being loaded anyways. It would be nice if this situation can be reviewed and addressed. Thanks.
Simon Steinbeiss referenced this bugreport in commit c649323dbd80f39b196ee748bc640037dc4837e8 Fix xfpm startup dialog ignoring response (Bug #13700) https://git.xfce.org/xfce/xfce4-power-manager/commit?id=c649323dbd80f39b196ee748bc640037dc4837e8
Should be fixed in git master now. Thanks for reporting this!