From an ergonomics point of view, I wonder if the clamp sitting horizontally on your belt would make the grenade easier to grab? As your hand goes to your belt its naturally positioned in such a way to grab the grenade “sideways”
As its pulled out of the clamp, whatever is used to retain the linchpin could sit (or hang) on the underside of the clamp and would simply fall out of the way when the grenade is er…plucked
Changed the clamp position so the nade can sit parallel so you can tie the pin to the vest so you could just pull it straight out and the pin would get yanked out in the process, I designed it to screw onto a molle plate so the orientation can be adjusted to suit