I agree, the majority of Knots will always have the ends of the knot facing towards the sides of the bag. I have seen many Croc Knots with the the knot tilted slightly to the side, the Taipei Knot (SS2010 in Tejus) has the knot sideways, as does the Metallic Mineral Knot from FW2009 and the Multistone Beaded Knot from FW 2008. Having said that, the majority of Knot Clutches with the knots tilted or sideways have not been on straight up, regular silk, satin or faille. They've been exotics or special seasonal knots.
If there's one thing I've learned over the years, it's that there is never any hard or fast rule when it comes to Bottega Veneta. What they choose to do for one season, they don't do for the next. I can be frustrating, that's for sure.