Or hit him with your iPad, oh ... that has to be stored too.
Hit him with your Steve Jobs biography (2.1 lbs, 0.95kg) that's OK to have out.
Or don't worry about it. Regulations on cell phone use are there because of the interference they cause with ground stations (cells).
Federal Communications Commission (FCC) rules prohibit the use of cellular phones using the 800 MHz frequency and other wireless devices on airborne aircraft. This ban was put in place because of potential interference to wireless networks on the ground.
Wireless Devices on Airplanes | FCC.gov
In theory he should be reported to the police for not following crew instructions. He is breaking the law, but so will be the guy hitting the G&Ts with the intention of driving later.
If flight safety was involved I'd be more concerned, but there is no compelling evidence to suggest there is. The US FAA is re-re-re-reviewing it