Most of the United States along with the entirety of Mexico were confused about what Mexican President Enrique Peña Nieto thought to gain for either himself or his country by receiving Donald Trump on Wednesday. One school of thought held that he had nothing to lose, what with his own approval rating at a sub-Trumpish 23 percent. Maybe, the thinking went, he would tell off Donald Trump to his face. After watching the joint press appearance afterward, however, it’s clear that this was the wrong way of looking at things. A better way is to work from the assumption that a politician with 23 percent approval has no idea what he’s doing.

The statement that will carry some stateside headlines was Trump’s response to a question about how they didn’t discuss which country would pay for the wall. Presumably they didn’t discuss this because even Trump, shameless as he is, would be too embarrassed to raise such a dumb campaign talking point in the presence of a head of state. Trump knows who his chumps are.

But Trump’s demurral was nothing compared with Peña Nieto’s response to the same question. Here, Peña Nieto had the immediate opportunity to humiliate Trump by flatly rejecting this ridiculous idea. He could have buried Trump and improved his own flagging fortunes. Instead, Peña Nieto reiterated some pablum about how they had a pleasant conversation, and how he didn’t want to meddle in the election, as if the very occasion wasn’t already an example of that. Peña Nieto was asked directly about whether his country would pay for a domestic American construction project, and he declined to answer. Probably he didn’t want to seem undiplomatic. Then for what possible reason did he want to meet with Donald Trump?

My theory: A not-too-bright president got his bluff called and had no idea what to do when Trump accepted his invitation. He offered the candidate a platform on which to look like something other than a completely ridiculous knuckle dragger, which many pundits will score as a grand slam for him. And Peña Nieto didn’t take his chance to shoot down what is the most prominently ludicrous political notion that exists within Donald Trump’s head. Maybe it’s not so ludicrous anymore. Maybe Mexico really will pay for the wall if this guy’s still in charge.

Update, 9:11 p.m.: And here’s the clean-up. Peña Nieto now says he told Trump privately that he would not pay for the wall. “Today was the first part of the discussion and a relationship builder between Mr. Trump and President Peña Nieto,” the Trump campaign said in response. “It was not a negotiation, and that would have been inappropriate. It is unsurprising that they hold two different views on this issue, and we look forward to continuing the conversation.”

Read more Slate coverage of the 2016 campaign.