I don't have a problem with that usage. 0% or 100% can be used as a figure of speech when the proper probability is small enough that x < .1^n (4 (or something appropriate) < n) in 0+x or 1-x. If others are correct that probabilities that small or large don't really have much human meaning, getting x closer to 0 in casual conversation is pretty much pointless.

Of course, a "~0%" would be slightly better, if only to avoid the inevitable snarky rejoinder.