In general the safety rules I was taught were defense in depth -- multiple failures need to happen before someone can get hurt. So, even when you have a holster

In general the safety rules I was taught were defense in depth -- multiple failures need to happen before someone can get hurt. So, even when you have a holstered firearm, pointing the muzzle away from people is preferable because then if it somehow does fail at least it's less likely to shoot someone. Obviously that's not always practical, but if you are placing a chambered firearm down on a desk, you might as well try to point it in the direction of least harm, it basically costs zero to do.