Joe Biden and Donald Trump are both old men, born four years apart during the 1940s. Biden is eighty-one and Trump is seventy-seven; the average life expectancy for men in the United States is seventy-three years. If Biden wins reelection, he would be eighty-five years old at the end of his second term; if Trump retakes the Oval Office, he would be eighty-one at the end of his second term.

While the name “Biden” has become a metonym for public lapses of memory and verbal slipups, Trump does not lack for senior moments of his own. Jamelle Bouie cataloged a few of them in a recent New York Times column, but they elicit far less coverage and commentary than Biden’s. Trump, according to Bouie, benefits from the “soft bigotry of low expectations,” because few expected him to become president or behave like a “normal” politician in the first place. So when he mixes Nikki Haley up with Hillary Clinton, or Kim Jong Un with Xi Jinping, or describes the workings of a missile defense system in a bizarre string of bleeps and bloops, barely anyone bats an eye.

There’s definitely something to Bouie’s argument, but I think the dynamic goes deeper. Trump gets a pass while Biden does not because this is ultimately not about whether Biden is too old to be president. It’s about whether he is too weak to maintain American power and protect American citizens in a tumultuous world.