Elon Musk's biographer, who was shadowing him, says the billionaire likely decided it was 'unwise' to post a baseless conspiracy theory about Pelosi's husband and deleted it

• Walter Isaacson said Elon Musk likely later thought it was "unwise" to tweet a conspiracy theory.
• On Sunday, Musk tweeted and then later deleted an unsubstantiated claim about Paul Pelosi's attack.

Walter Isaacson, an author who has been shadowing Elon Musk for a biography on the billionaire, said Musk quickly rethought his decision to post an article on Twitter that promoted a baseless conspiracy theory about the attack on Nancy Pelosi's husband.

"He does that very often, which is very impulsively tweet things out and then I think — clearly by the fact that he deleted it — he thought, 'Well, that ended up being something that was unwise to have out there,'" Isaacson said in an interview Monday with CNBC Squawk Box.

The biographer shadowed Musk over the past week as the billionaire followed through with his plans to buy Twitter.

"There are times when he just goes off on the corner and he may chuckle, he may be upset, he may be mad, and he'll tweet something out," Isaacson said, noting he thinks Twitter would benefit from a five or 10 minute delay that would ask the user "You sure you wanna send this one out?"

On Sunday, Musk responded to a tweet from Hillary Clinton in which the former first lady criticized the Republican Party for spreading "hate and deranged conspiracy theories" that she said encouraged the attack on Paul Pelosi on Friday. In his response, the billionaire linked to an article from the Santa Monica Observer, an outlet that is known for spreading false information in the past, and said "there might be more to this story than meets the eye." The article presented an unsubstantiated claim that Paul Pelosi had been under the influence of alcohol and engaged in an argument with a male escort at the time of the attack.

The billionaire deleted the tweet within a few hours and later responded to a story from The New York Times regarding his tweet with a joke.

Isaacson told CNBC that Musk shouldn't have posted the article. Though, he called content moderation a "difficult question."

"If somebody says, as he did, 'There's a tiny chance that this is true. Is that something that to be tweeted out?' In my opinion, no," Isaacson said. "I think that he's very unfiltered, but that's something — especially the tweets you're talking about — that I don't think serve the platform well," he added.

However, the biographer questioned whether much of Musk's success could be attributed to being "unfiltered," comparing him to Apple's Steve Jobs.

"To what extent can you separate the unfiltered behavior that's bad from the behavior that allows them to discover, great things or to create the Apple computer or to create SpaceX and Tesla?" Isaacson said. "And to what extent are those interconnected? Is it just a holistic person there in which the unfiltered nature of the thought is just who he is?"

On Friday, Bloomberg reported that hate speech had surged on Twitter in the wake of Musk's acquisition. The same day, Musk said Twitter will form a content moderation council. The billionaire has said in the past that he plans to avoid censorship that extends beyond the letter of the law and reinstate accounts that had previously been banned.