“Trump is innocent!” Mr. Shroyer shouted.

Mr. Shroyer’s stunt during the widely televised hearing came despite efforts by major technology companies to wipe Infowars and most of its content from their platforms, as they struggle to contain the spread of misinformation online.

[From The New York Times Magazine: I worked for Alex Jones. I regret it.]

Last year, Apple, Facebook and YouTube, which is owned by Google, severely restricted the reach of Infowars and Mr. Jones after years in which they spread dark conspiracy theories about the Sept. 11 attacks, the Sandy Hook school shooting and the Boston Marathon bombing, among other tragedies.

Twitter also banned the accounts of Mr. Jones and Infowars last year, saying both had violated its policies, which prohibit direct threats of violence and some forms of hate speech but allow deception or misinformation.

Yet Mr. Shroyer remains active on Twitter, where he has more than 120,000 followers, and effectively used the site and its streaming video service, Periscope, to promote his interruption as Mr. Nadler began his opening statement.

When it banned Mr. Jones and Infowars in September 2018, Twitter said it would continue to evaluate reports about other accounts associated with him and his website and would take action if they violated its rules. On Monday, the company declined to comment specifically on Mr. Shroyer’s account.