The problem is the quoted bid/ask range is normally much wider tahan what you can actually trade at. As you say why can't the actual spread at time of deal be used as basis for wherther a buy or sell; as if stockmarket still uses pen and paper.
Stew thinks his posts will influence the price. As he has made clear he is in for a trade so wants a low entry point; his type do make these BBs so much fun but you do have to worry about their mentality.