That is a claim the Warmbier's made, not Trump. That may sound like a meaningless assertion but don't you think it's a stretch to say that he exploited the situation for political gain because he did not correct their story(from a live interview I might add) esp. on Twitter?

Even using the word 'torture' at that time doesn't seem unreasonable or part of a conspiracy. What is the proper motive? To get people to label DPRK a terror sponsoring nation?

It seems like a very high expectation to place on a president to correct any false narrative being perpetuated or else be party to promoting them for political gain.