Obama Wearing "Mask of Decorum" to Influence Trump

Everyone sometimes like to dress up as something they're not. Some people dress up as doctors or werewolves. Obama dressed up and pretends to be capable of decorum.

This bit comes from Remnick's fawning profile of Obama in the New Yorker. 

Although Obama and his aides had long been alarmed by Trump’s disturbing rhetoric and loose grasp of policy, they decided that the best path forward was to assume the mask of decorum. It was a matter of amour-propre, but—again—also of tactics. To have any chance to influence Trump, they had to avoid any trace of the contempt that had once been so pronounced.

Another excerpt mentions Obama  "putting on a mask of generous equanimity for a visitor whom he had every good reason to despise".

For Obama decorum is a mask. What everyone saw was a disguise. And the White House wants its base, the New Yorker readers, the left-wing urban elites to know that this is just a show.