Mike’s Baseball Rants questions Bud Selig’s motives in the deal as well.

I just have to ask what is it that causes Bud to be so partisan when it comes to the Red Sox. I know that Bud, as a young, unctuous used car salesman in Milwukee, was upset when his beloved Braves moved from Milwaukee and that later spurred him to wrest the Brewers from Seattle. Maybe when he harkens back to the Braves moving, it?s not the move from Milwaukee that so aggrieves him but rather the move from Boston some 13 years earlier.
Perhaps he feels that he has to give back to the Beantown community in the form of Cliff Floyd, Kevin Millar-san, extensions to finalize the Curt Schilling deal, the gentle nudge to ensure that the Red Sox acquire the best shortstop in the game since the second-best one was sticking up the field, and a partridge in a pear tree.
Either that or John Henry has a Paris Hilton video starring Bud. Take your pick.

I think it’s pretty clear what’s going on. In return for letting Henry buy the Red Sox when there was likely a higher bidder, by letting the Red Sox acquire whomever they want, Bud gets a large market team to support his small market socialism. It’s Bud buying power.