Obama didn't do it so we won't get a chance to test that theory. But my point here is the lack of consistency. In 2017 Trump was more or less threatening Nuclear War. In early 2018 it seemed that we'd moved to a position where North Korea might denuclearise, which would have been brilliant -- except in the event the historic summit between the two led to very little of substance and arguably saw the US gave too much away. Then in the next meeting Trump walked away quickly. Not unreasonably either, since it seemed earlier that North Korea had promised much but delivered little. And now Kim Jong-Un offers Trump a photo opportunity and he pirouettes again. What next? There's no consistency at all here, and I think it's quite reasonable to question if Trump actually has a plan here.
It's the same with Huawei. I'm not really following that story fully, but as far as I was aware the US had declared Huawei to be a security threat, and was trying to persuade other countries of the dangers they posed if allowed too much access to 5G networks, to the extent of stopping US companies from dealing with Huawei. All of that has been undone after basically two hours of conversation in which I'm not sure that China's promised anything, and makes a mockery of US intelligence in the process. Do we really think that if Huawei posed a security risk before then anything President Xi says is worth listening to? Trump was better sticking to his earlier line.
Also, consider the situation in Iran. Trump has walked away from the Iran Deal, then criticises Iran for breaking it, and was essentially 10 minutes away from open hostilities. Given how Trump's reacting to Kim's overtures, what if Rouhani or Khomeini tried the same thing? Offer Trump a handshake and a photo op and then everything changes. Wouldn't surprise me in the world. US foreign policy at the moment feels whimsical rather than considered, and that's worrying.