That knife is tip-down only carry. If it's opening in your right pocket, then there's not a lot you can do to prevent that. On this forum people generally prefer tip-up carry (where the pocket clip is oriented such that the blade tip points up, rather than down, while in your pocket). This means that the blade is stopped by the seam of your pocket if it opens while being carried. Tip-down carry is doable if the knife has a strong enough closed position detent, but I'd bet that the M16 doesn't have that based on the ones I've seen. You can try carrying it in your back right pocket or front left pocket, but I'd recommend just returning it and getting something else that works better without those compromises.
I've never seen a knife with a seatbelt cutter oriented on the flipper tab. That sounds like a horrible idea, and one that could cut your pants just from putting it into your pocket incorrectly.