Begging your pardon, that's the way Gerald O'Donvan (AKA GOD) built all (as far as I know) the Raleigh SBDU bikes. It's not ugly, in fact it's rather attractive in a minimalist sort of way. I do realize, in this particular case, that there would be an unused cable stop on the down tube. While a derailleur with an integral stop is to be preferred, if one wasn't to be found this [routing under the BB] would be a perfectly suitable solution.
I'm talking about routing a piece of housing from the downtube cable stop, under the BB and then having the end of it stick up loose behind the seat tube. Is that what you're referring to? If so, then yes, it is ugly and sloppy, and I don't care who did it.