Trump’s iPhone has been scrubbed of all of its apps except for Twitter, tech news site Axios is reporting, citing “top White House officials.” According to the report, those officials are concerned that if their boss has too much free time, he’ll post tweets spend it posting fiery tweets or lashing out at what he sees on cable news. To avoid that, they’ve loaded his schedule with work, the report says.

But exactly why one target of their concern—Twitter (TWTR)—remains on Trump’s iPhone, is unknown.

Get Data Sheet, Fortune’s technology newsletter

Although Trump had been using an unsecured Android phone when he took office, the White House tweeted in March that he had switched to an iPhone. Many of Trump’s tweets have also come from an iPhone.

There could be a number of reasons why the president’s iPhone has no apps except for social media. It’s possible, for instance, that the device was intentionally modified to reduce the risk of hackers getting access to confidential information—something that is unrelated to the president’s tweeting.

Still, considering Trump’s habit of using Twitter to share his thoughts and policies, it’s perhaps no surprise that it’s the one app that survived the scrubbing.