Elon Musk has tweeted again about a man he had previously accused of being a child abuser.
"You don't think it's strange he hasn't sued me? He was offered free legal services," Tesla's chief posted.
The tweet comes more than a month after Mr Musk apologised to the British diving expert Vern Unsworth for calling him a "pedo".
Critics suggest the latest message is further evidence of the tech leader's erratic behaviour on social media.
Mr Unsworth has told the BBC that he does not want to say anything at this stage.
Tesla's shares fell about 1.5% in early trade despite the Nasdaq, on which it trades, opening higher.
Mr Musk has been embroiled in another Twitter-related controversy over recent weeks after tweeting that he was considering taking his car firm private, adding that he had secured the funds required.
That caused major swings in the company's share price and subsequent claims that his message had been misleading. Mr Musk later said the firm would stay public.
The US Securities and Exchange Commission is now reported to be investigating the matter, and some Tesla investors are suing the firm over the tweets.
Mr Musk's latest tweet was written in response to a former journalist, who had accused him of hypocrisy.
"Your dedication to facts and truth would have been wonderful if applied to that time when you called someone a pedo," posted Drew Olanoff.
In response, the tech entrepreneur not only questioned why Mr Unsworth had not taken him to court but also attacked Mr Olanoff for not carrying out his own investigation into the matter.
"So you actually did nothing and yet imply you are a truth-seeker," wrote Mr Musk.
The US business leader had originally tweeted about Mr Unsworth in July.
The two had been involved in a dispute over Mr Musk's offer of a mini-submarine to help rescue schoolchildren trapped in a flooded cave network in Thailand.
When questioned about this, the Briton had told CNN that the submarine was "just a PR stunt [that] had absolutely no chance of working".
Mr Musk responded with a series of tweets, casting doubt on Mr Unsworth's character without providing supportive evidence.
They culminated in a post that described Mr Unsworth as a "pedo guy" and a follow-up saying "bet ya a signed dollar it's true".
Mr Unsworth subsequently said he might take legal action.
The clash appeared to have been resolved after Mr Musk deleted his offending tweets.
"His actions against me do not justify my actions against him, and for that I apologise to Mr Unsworth and to the companies I represent as leader," Mr Musk tweeted on 18 July.
Mr Musk has more than 22 million Twitter followers and frequently interacts with users who refer to him on the platform.
Many of his messages have led to positive coverage about Tesla and his other companies in the press.
But some observers have suggested Mr Musk should curtail his use of social media bearing in mind he has said he is working 120-hour weeks, is under great stress and is making use of the sedative Ambien.
Mr Musk, however, has denied his use of the app was a distraction.
"I think sometimes people think I spend a lot of time in Twitter," he told the YouTuber Marques Brownlee earlier this month.
"Actually, it's like almost nothing. Most of my time is spent... going round the [Tesla] factory... and if I'm not here I'm at the Giga [battery] factory in Nevada."
Mr Musk's younger brother - who is a board member of Tesla - defended his sibling's behaviour in a recent interview with the New York Times.
"The reason Elon seems to attract drama is that he is so transparent, so open, in a way that can come back to bite him," said Kimbal Musk.
"He doesn't know how to do it differently."
But one leadership expert suggested some of Mr Musk's behaviour was unacceptable.
"Conventional business leaders are far more careful in their behaviour - you don't find FTSE 100 chief executives shooting from the hip like this because they are advised it would be detrimental to the interests of their companies," Matthew Gwyther, ex-editor of Management Today, told the BBC.
"But there can be a lack of humility that comes with being involved with big tech.
"If [the latest tweet] adversely affects the share price then Tesla's board members may feel duty bound to do something about it.
"But one way or the other, it's not the way you'd expect a person with that degree of power and responsibility to behave."