Fred, the determination on that first out was over when contact was made. The short stop had already missed the bag going by, and was then setting up to convert a double play attempt.
The runner did not prevent that first out from being made.
It could be assumed the runner did something to break up the throw to first base, and that runner could be called. Two never would in this instance unless the runner had caused the short stop to miss the tag of second base. He didn’t.
One: of course he can't award two outs on the play as it was called in real-time, because Utley is already out. They call that out ["In the vicinity"] ALL THE TIME. Yes, they can still call it interference if they deem the slide illegal and unrelated to his own attempt to reach base safely. In which case the batter is also out. Result: one put-out, one out awarded. Double Play.
Two: they call Utley safe on the replay. This, they completely munged up. Someone should have thrown the ball to the second baseman to step on the bag before time was called for review, because Utley NEVER touched second. Now Utley is OUT, regardless of what the replay says, because he never reached second. That is what the Mets should have done.And to keep them from doing that, Utley should have gone to second base.
Even so, in the review, because Utley did not tag second, the shortstop still has a tag play on him. The ump at second can rule that Utley left the base path to interfere with the fielder [that call is made from time-to-time] or made an illegal slide to interfere with the tag -- because rolling into a fielder is illegal -- and therefore both he, and the batter are OUT. Result: two outs awarded. Double play.
You may think it unlikely they would award two outs in the second case. OK. I agree. However, the ump is not restricted to a case where the runner interferes with the fielder literally in process of fielding the ball in order award two outs. That is the most common enforcement, but that is not the complete discretionary authority given to the umpire under the rule.