Ram does make holders which fit some phone sizes, like a case the phone snaps into. Though not all phone sizes or models. So this way you don't have to use the "X" clamp if you are worried about it popping out of it.
Never used one myself, but Amazon offers a special tether for use on motorcycles (with the X-Grip): https://www.amazon.com/Mount-Tether-Small-X-Grip-Cradle/dp/B017STCELI