Kieran, if they didn't get a caution flag then Dixon would surely have pitted and Dario would have been left with a decision. If Dario stayed out in that situation the roles might have been reversed, with Dario running out of fuel on the last lap and Dixon cruising by for the win. If both pitted Dixon would still have the track position advantage.
That's not what happend though and none of that proves the conspiracy theory.