Scott-
Very interesting point about the use of outside/unlicensed oddsmakers. However, oddsmaking is not a precise discipline and more of an art where information like weather, injuries, etc. come into play.
Don Best is a valid tool (just like reading the sports section of a newspaper) for the oddsmaker to use. He doesn't have to agree with the Don Best number (which there is no single number, but a list of opinions of different books). Also, line moves on Don Best can serve as an "alarm" to the Vegas sportsbook's licensed oddsmaker to "double check his math" or look at the current money position on the game or to suspend action on the game.
Don Best is an information tool and should be a valid source of information for any oddsmaker. Injury reports and other alerts would be pretty darn useful to an oddsmaker.
Ultimately, the Commission in Vegas cares that the operations are not fronts for organized crime and that the casinos can cover any action they take so the public is not at risk.