Saying no Muslim should ever be President is not smart. See sample reporting; here, here, an ocean away here, and not surprisingly, here.
To be wholly honest, aside from Bernie and not knowing much about Martin O'Malley and thinking Lincoln Chaffee would be the best Republican if still of that party; Keith Ellison would be a better person for President than Hillary, and better than any of the Republicans, notwithstanding he is a Muslim and not in any degree because he is a Muslim.
Ellison, instead, is closer to Bernie than any of the declared wannabes, including Biden who so far demurs. Yes he is an office holder not an outsider, but so is Bernie. The two of them are saner people than any of the Republicans, in their public statements and on their records, with far, far, far less narcissism than Clinton, Trump or Fiorina and without the email and Foundation and Benghazi baggage dogging Clinton.