Taking to Twitter on Sunday, Musk said to British cave explorer Vern Unsworth, "Sorry pedo guy, you really did ask for it". The rift between the two men started when Unsworth said the small submarine that Musk delivered to the cave site had no chance of working, calling it a "PR stunt". The British diver went on to say Musk "can stick his submarine where it hurts".
Musk posted the baseless accusation shortly after.
Musk had already attracted criticism for his approach to the Thai rescue after Narongsak Osatanakorn, head of the joint command center, said the mini-submarine was sophisticated, but not practical for the operation. "He had no conception of what the cave passage was like". The caver said, "I believe he's called me a pedophile".
Musk's outburst came just a week after he said in a Bloomberg interview that he would try to be less combative on Twitter.
Tesla's stock price was down more than 2 percent Monday in premarket trading on the news that Unsworth reportedly is mulling legal action against Musk, suggesting that investors may be growing restless with his shenanigans.More news: John Isner can't win this epic marathon match at Wimbledon
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Unsworth concluded this portion of the interview by claiming that Musk had been quickly asked to leave the cave during his much-tweeted-about visit.
"Bet ya a signed dollar it's true", he wrote in another tweet that has since been removed.
"It's not finished", he told Australian network Channel 7.
He lashed out at critics of his involvement in the Thai soccer team rescue.. He said Musk, whom he had never met, must have a "bruised ego".
Last week, Musk also took to Twitter to pledge to help Flint, Mich., residents affected by the city's water crisis, replying to a user that he would commit to "fund fixing the water in any house in Flint that has water contamination above FDA levels".
Tesla stock fell almost 3 percent Monday to $310.10 even though the broader market was up slightly.