The ball neither needs to pitch nor strike inline, if it was coming from outside off into the stumps, in order to give Out, Leg before wicket.
This is the basis of the original decision. The two flags for Pitching - inline and Impact - inline only some green if they are actually inline, even though that is not always necessary for Leg before wicket. As long as the third and important flag (Wickets - hitting) is green, the correct decision is Out.
See Law 36, part 1.2 for the pitching and part 1.4 for the contact.
Note that this assumes "the striker has made no genuine attempt to play the ball with the bat". As this aspect of the law comes outside the scope of UDRS, it must be assumed the umpire decided no genuine attempt to play the ball was made.