Obviously you should always always always have eyes and ears on when shooting. That said, an AK is one of the easiest guns to build from a kit and the bolt and barrel are both professionally machined steel, so if it chambers a round it's probably safe to fire. The guy's not completely nuts.

To be fair, you don't know how many rounds he fired before the pic was taken.

The picture caption is "Firing my new AK. The rifles are popular because they work—every time." ... and his finger is on the trigger, which you're trained never to do unless you're prepared to fire ... so are you assuming he put his glasses on after he raised it into the firing position, and put his finger on the trigger?