Nup. Sharp knife + Soft skin + Flopping about in waves = high risk
If a blade like the Spyderco or similar makes contact with your flesh it will
That's why hook knives were invented. Sharp knife with built in safety guard and almost no way of getting your flesh into the blade.
When I think about it there's only two times you would want a knife in kiteboarding:
1. You've got rolled in the surf and tied up by your lines (or similar including tied up and now kite is powered up
2. Your kite is in a death spin and all your quick releases are not working.
For 1 you're better off not panicking and just staying alive and not dicking around with knives in general. If you need a knife a hook knife would be appropriate because you care cutting close to your body and limbs. A hook knife is going to be fairly reliable in that case.
For 2 where you might be trying to cut through your depower line and the whole thing is out the front of you, away from your body, then a Bear Claw knife might be appropriate.
It's starting to get a bit silly when you have to load yourself up with a serrated rescue knife and a hook knife and all sorts of stuff because you are paranoid about an event that is fairly rare.