JAWS is an F-16 guy in his unit's engine shop. He knows his stuff.
As he said, the jet you've shown in the pic isn't undergoing 'maintenance.' It's merely getting a quick check. Opening up the panels over the gun isn't a 'quick check.' that is only done during routine inspections during phase or when the gun breaks. Either way, the jet's explosives (weapons and cartridges in the pylons/bomb racks) are downloaded. A jet in a hangar, for obvious reasons, has no live ordnance loaded, which is why finding photos of A USAF JET depicted as such isn't likely to happen.
The super Hornet pic you referenced is also only undergoing a quick check. the avionics panels along its nose are quickly opened and checked during the preflight and post flight, but the same rules apply--before it's towed into the ship's hangar bay, all explosive ordnance is downloaded.