Good question. I was going off the linked article which states:
> In the middle of the divider was a tiny gate, just large enough to admit one molecule of gas.
Still, that's quite a small hole relatively speaking. So you'd have to be fairly precise about both position and velocity. Potentially more than is allowed by Plank's constant. I dunno though, this isn't one of the counterarguments in the Wikipedia page, so probably you're right.
