I guess you would have to act fast to nick it if he is doing around 80.
I mount my car Tom Tom on my bars if I am off to a new place and it important to be there on time, I purchased a case mount on Fleabay, its not the best piece of equipment but it does the job, and as its on the bars behind the screen its ok in the rain. But I remove it when parking up, as I do my Go-Pro.