Fair point if the problems are just crashes, but I wouldn't be surprised if Belichick was getting that frustrated over much more minor things at a time when the game is not on the line. In my experience many older people have extremely low tolerance for usage of technology not going perfectly.
For example, I could picture BB chucking the tablet from something like a slight lag when navigating menus or even just dissonance between how the app works and how he expects it to work (regardless whether or not poor design is to blame).
