Here's what I found on this website: https://www.phrases.org.uk/meanings/as-pleased-as-punch.html "Punch and Judy shows, the popular summer-time entertainments on British beaches, have been somewhat in decline from the latter half of the 20th century onward, due to them being seen as politically incorrect. That's hardly surprising as the main character Punch is a wife-beating serial killer. It doesn't sound like Punch was a very pleasant character at all and not very pleased."
What does a wife-beating serial killer have to do with trump? Well, you can make up your own joke about that!