Trump is Scared of the Fellow Class
The business class is now very frightened of an imminent recession, and they have been using their lobbying power to read the riot act to Trump and underscore their disfavor with his trade war. This is why he made an attempt at being more cooperative at the summit.
There is No Better Trump
Trump has made fleeting attempts at being presidential before. The key word here is fleeting. The attempts never last. Trump lacks the maturity and discipline to stifle his gut impulses. As such, he will go back to being a combative buffoon, and sooner rather than later.