It’s a joke which uses humorous juxtaposition. Donald Trump is very different from a drag queen, so it’s funny to juxtapose the two. For example, it would also be funny to see Trump made to look like a fashion punk.
Trump is macho and takes himself very seriously, wheras drag performers are femme and tend to be whimsical. Also, while drag queens tend to be awesomely comfortable with their appearance, Trump would presumably be horribly embarrassed if he was made up that way. Which is also funny to imagine.
