How was the Flydubai pilot who attacked his co-pilot cleared to fly?

A Flydubai flight heading to Tel Aviv was diverted after a fight between the pilot and co-pilot, with the co-pilot stabbing the captain. Captain Smit Machchhar, an Indian national, managed to open the cockpit door despite the attack, preventing a midair disaster. The UAE has launched an investigation to uncover the details, motives, and possible terrorist links, while Saudi Arabia has not yet provided any updates.