If they join Belt and Road, it won't be because of Trump. Are you aware who Columbia's President is?

Yes. But Trump's actions can't be both consequential and irrelevant - strongly shaping Colombia's behavior for all the intended consequences, but having no impact at all on the unintended ones.

When Trump forces the country to publicly bend the knee like this, it accomplishes his short-term objective - but it makes the country and the electorate far more receptive to the possibility of opening up more and more to the Chinese. Politics exist, and the many reasons why Colombia had been moving more modestly in the direction of Belt-and-Road rather than just signing on were a function of that politics. It's a golden opportunity for China to appear more as a viable strategic partner that serves Colombia's interest rather than being a carpetbagger.

So when Trump throws a hand grenade into Colombia's domestic politics and foreign policy like this, it's going to have an effect. Trade-offs exist.

I agree that Trump will disclaim any responsibility, of course - and I expect his supporters will as well. But that doesn't make this a smart thing to do.