For some reason this just doesn't seem right, either ideologically or conceptually.
The idea of a guillotine is to remove the head, and so the basket is put under the guillotine to catch it. In this case, the basket's put under the yukkuri's ass and that kinda defeats the purpose ideologically. Unless this is an ass guillotine. >_>
Not to mention a yukkuri IS a head anyway. So you're pretty much chopping a head in half using a guillotine.
Then again a yukkuri is a manju. Shouldn't a nice kitchen knife be easier?