See, this is one of those times when, as a GM, I’d let coolness trump RAW in a hot second.
Player:  Nice.  I duck under the ghoul’s claws and then, while he’s overbalanced, trigger my force rings, sending him sailing into the other ship.  Can I use riposte for that?
Me: Why not.  Awesome.  How much damage?  Okay, you shatter most of his bigger bones.  His broken corpse sinks beneath the waters, leaving nothing but a greasy splotch to mark his passing.  Now… 
That said I get that you’re handing the PC a bigger advantage than Riposte is supposed to confer, so I probably wouldn’t make a habit of it.