Glad we solved that one. Now the Sherlock Holmeses over at Halos Heaven can move on to other pressing issues such as the Yankees' rampant steroid use, FOX's blatant favoritism towards them, and the fact the umpires are on the Yanks' payroll. (Not kidding, they have suggested all of those things in the past three days.)
The initial reaction by the league had been that the video plus still pictures they have of the incident were inconclusive if Rivera actually spit on or near the ball. But after further review of what they had, the Commissioners Office determined that Rivera was not spitting directly on the ball.
On a couple of the still pictures in MLB's possession, it apparently looks as if Rivera is spitting near, but not on, the ball. Also, as even the league office is aware, Rivera is a player who spits constantly while in action.