So, Magic, Skaven Bullshit, or Really Big Explosives aka Specific Flavor Of Skaven Bullshit.
I recognize that from our observable data, Max should be safe. I just don't trust the unknowns enough to risk him being on a gyrocopter until he ends up able to survive a crash.
Most magic wouldn't be enough, and nearly no skaven bullshit would be either. There's also skaven bullshit or magic that could hit him wherever he is, so it basically evens out.