The statement was "there's no promotion cd out there. so this means it was never a promotional single...". Simply put, it's a good old-fashioned "You can't prove it, therefore I am right" argument. Argumentum ad ignorantiam. LP says they had a song called Pictureboard, but we've never seen it. We cannot prove its existence, therefore LP is mistaken! The song does not exist!
It comes off as elitist and condescending.
Let me make this clear. My point is not that With You is a promo single. That's only a side thing I'm trying to figure out. The point is, you can't say IT DOES NOT EXIST, simply because no one can PROVE it exists.