I'm impressed it's Meroune's claspers instead of the guy just wrapping his legs around her hips and thrusting that way.
I don't care how slippery you are, Princess, but he's not going to slip anywhere with your claspers above his legs and his legs constricted enough to not slide down over your main swim muscles which, by the way, are WIDER than your hips. He'd be literally wedged into place until he lets go, and since this way you two can go faster than what must be really slow and awkward here... I think you'll both like it.