Which has always been code for "I'm privileged enough not to be affected by this, and I do not care how it affects others."
I don't know how much his actual political motivations factor in, compared to ratings.
If he gets political, he competes with the other hosts for the same audience, and loses (potentially very big) because he's just not as funny.
If he doesn't get political, he gets to scoop up whatever audience of conservatives are too outraged by anti-Trump humor to watch the other hosts. He still loses in ratings, but he gets to keep his head mostly above water without actually having to compete in terms of comedic quality at all.
If I were an extremely mediocre comedian like Fallon, I'd probably take the Late Night Wellfare option, too.