VS's bassinet on the A340-600 is designed so the child does not have to removed during turbulance, its not the sky cot design found on the Boeings, it reminded me of a baby bouncer that attached to the wall and the child was then strapped in like they could be in a infant car seat.
I've used a sky cot also and agree that you wouldn't ever leave a child in them during turbulance, i've only had use of a bassinet/sky cot on VS however so couldn't comment for other airlines