"A critical function of our service is providing a place where people can openly and publicly respond to their leaders and hold them accountable," a Twitter spokesperson told Business Insider. "With this in mind, there are certain cases where it may be in the public interest to have access to certain tweets, even if they would otherwise be in violation of our rules."
Twitter allows government officials to tweet things that otherwise may be removed for violating its rules due to a public-interest exception.
"At present, we limit exceptions to one critical type of public-interest content -- Tweets from elected and government officials -- given the significant public interest in knowing and being able to discuss their actions and statements," the Twitter policy states.
Twitter added that, regardless of public interest value, tweets from a world leader can still be removed if they promote terrorism, make direct threats against an individual, post private information or intimate photos without the subject's consent or engage in child sexual exploitation or encourage self-harm.
Though Twitter hasn't outright banned Trump's tweets, it has taken other steps to restrict some of them.
Among these steps, Twitter placed a fact-checking label on Trump's tweets for the first time in May over potentially harmful or misleading information about mail-in ballots. Also, in May, Twitter hid Trump's tweet, "when the looting starts, the shooting starts," behind a warning label where users had to click on "View" to see it because it violated the company's rules about glorifying violence. And just last month Twitter hid another of Trump's posts behind a warning label over spreading COVID-19 misinformation.