Well, the main issue with Trump is that he’s in the White House and messing with the country and the world at large in very serious and problematic ways.
Making fun of him is an all-too tempting outlet for the upset. Unfortunately, it doesn’t really address or solve the problems. It’s not going to change any minds that weren’t already against him. And, it tends to close off this semi-supporters, who start to object to what starts to seem like bias and just “people who hate Trump, and are being silly”.
It would be a lot more effective if we could calmly stick to the near-infinite list of serious objections to his policies, appointments, edicts, conflicts of interest, inconsistencies, lies, crimes, and other material concerns, expressed calmly, soberly, and accurately.
As for the specific question here as written, while it may be a moral issue to make fun of people with serious issues, in this case he’s also a high-functioning terrible, terrible person doing massive damage of many sorts, so I don’t feel bad about it, but I do think it is a mistake of our own to focus time and energy on making fun or him or making extreme comments, regardless of how accurate and deserved we may think they are.