Is the president of the us required to wear a flag pin on his suit?

Yes and no.

The straight answer is no. The president isn't even required to go to college. All you have to be is 35+, American born, and have lived in the US for 14 years. That's it. But being the President of the United States is the hardest job in the world, but also the most honorable, and therefore, the most competitive. You want to be the best you can for the job, and look the best. So realistically, if you want support for your party, lobbyists, corporations, politicians, and of course, the people, being clean shaven, professional, wearing a suit, donning the pin, and being educated is practically a MUST.

The presidents wear pins to look patriotic, and show American pride. It looks better for the country's leader to seem like they love America that much. Me, I wear the flag pin on my lapel almost every time I wear a suit.