'The not out decision was reviewed and upheld but Hawkeye had the top of leg stump clipped. Had Trott been given out and himself appealed, he would have been given out according to the protocol.'
So to summarise: Trott was, potentially, not out and out. Kurt Vonnegut [or Schrodinger] couldn't have done any better.
The problem here is not the use of technology, it's the application. By giving the power of umpiring to the players, decision-making has essentially become politicised. By allowing two incorrect appeals, informed decision-making has become arbitrary. As I've blogged before, the proper solution is to hand the technology entirely over to the umpiring team, and have each decision reviewed by the third umpire, who can then feed back in the way he usually does.
The current system could only possibly have been designed by a committee, almost certainly after lunch...