The part you've highlighted in the paragraph from the comprehensive rules still seems to apply. If each target must receive one of whatever is being divided, then if something has been chosen as a target, then it must receive at least one damage. Furthermore, the ruling that Matt cited specifically states that, while X may be zero, if it is, then the spell has no targets.
Ok, then I was right then.
Ok. I'm not very coherent at 3:00 AM.
