According to the United States Code, which has a special section for commemorative coins: “No coin issued under this subsection may bear the image of a living former or current President, or of any deceased former President during the 2-year period following the date of the death of that President.”
Archive article: https://archive.is/28sTn
I got permanently banned for commenting, “He should have spray painted a swastika instead” in response to a photo of a guy spray-painting USA on a presidential plaque. Apparently that comment was “inciting violence.”