There is no excuse for this. He could have easily killed himself or anyone else in the home. The first thing you do when beginning to clean a firearm is to eject the magazine and check the chamber for rounds. Twice. If it’s a revolver then open the cylinder and remove any cartidges present. Even if you just checked it 10 minutes ago and you absolutely know there’s no live round in the chamber you still do this. Actually, you should do this not only when cleaning a firearm but anytime you pick up a firearm. This is firearm safety 101.
Thanks for the primer on firearms safety!
And if anyone out there is not going to take the time to learn and practice such techniques, please, do NOT own a gun!