The cartoonist is saying that "challenging Chump" is a seemingly hopeless task, but DeSantis will do it anyway. Just as Don Quixote tilted hopelessly at the windmills of Spain.

But this implies some kind of romantic admiration for DeSantis that really shouldn't be there. It's NOT that Chump deserves to be the candidate because he's the best choice. It's that he won't go away, ever - and the Grand Old Idiots Party won't summon the cohones to replace him with something better. Even if DeSantis were better - and he truly isn't - he'd never get the chance.

So it's hopeless, just like tilting at windmills.