Perhaps, but on the other hand, would anyone actually have confidence in him then sticking to what he says. Is there any actual point in negotiating with him?
Certainly. He's shown himself to be quite willing to listen. He postponed major Chinese tariffs on multiple occasions, referencing their good faith actions in negotiations. That was worth their time by itself. In the case of Mexico, he negotiated and signed on to the USMCA, which if Pelosi would pass it, would get them out of the current Tariff battle. By giving them collective bargaining and minimum wage, he would reduce their ability to undercut the US. He wants to be taken seriously as a negotiator. He'll gladly remove old agreements that are no longer in our best interest, but he'd be loath to remove his own accomplishments without strong reasons.