I still don't get that line. If VegasInsider accepts bets (idk, do they?) you have to feel like the money comes in heavy on UK if the line is UL -2. Vegas odds aren't about predicting the final margin. Ideally it's about setting the line where the books receive equal money on each side, and thus they guarantee profit from the "juice." At UL -2, you have to feel like money floods in on UK, at which point Vegas risks their profits in the event UK covers. Unless of course there is equal money coming in at UL -2, but I think even UL fans are scratching their heads at that line... I'm not familiar with VegasInsider, do they accept bets? None of the books that I know of have made lines available yet.
Unless maybe they open it low to generate early cash flow, with intentions of adjusting it later to even the money out. Probably some people betting the game at UL -2 that otherwise wouldn't have bet the game at all.