I don’t think flying is the root of the problem.
But the IfW Kiel is allegedly insisting approval for his trip ran out on September 10 and he must return immediately by plane.
He should have been back weeks ago. They want him back quickly, not over a month from now. He’s already proven himself to be unreliable and unprofessional, so I’m not surprised the institute isn’t being more flexible than they already have been. He could have avoided flying by planning ahead. Jobs come with responsibilities.
He’s already been given several weeks of leeway, which is a LOT more than most of us could expect from our employers.