It's not rocket science, the law is very clear. You cannot use a two-way device capable of receiving and transmitting data UNLESS it is in a mount. Laying on the pax seat doesn't count, flapping in a cup holder doesn't count, it has to be mounted. Once it is, you can no longer be charged under this law.
Instead they'll charge you under not being in proper control of a vehicle, which is a law that's been in place for years. Doesn't matter then if it's in a mount or if it's a factory dash install or you're reaching for a KitKat.