He said he had not seen Unsworth - whom he dismissed as "this British expat guy who lives in Thailand" - during his brief guided tour of the cave system and suggested that, therefore, Unsworth had not actually participated in the rescue operation.
Musk responded by saying Osatanakorn was "not the subject matter expert" and that he had been "inaccurately described as rescue chief" and should have been labeled the "former Thai provincial governor".
In between claiming to have proof that his submarine could have worked, he insisted that Unsworth wasn't even part of the rescue team and, consequently, he was just some guy looking for publicity.
Musk shot back on Sunday on Twitter: "We will make one [video] of the mini-sub/pod going all the way to Cave 5 no problemo". "Sorry pedo guy, you really did ask for it", he wrote.
Shares of the electric vehicle maker were down 3.5 percent in late-morning trading at $307.82 on news that Musk could face a libel suit over the episode.
Mr Musk has become embroiled in a series of spats with the news media - chastising reporters for focusing on accidents of autonomous cars instead of their safety potential, and accusing one news organisation of being "relentlessly negative" about Tesla.
He then reportedly went after Unsworth, calling him a "pedo" in a now deleted tweet. Asked which law firm he would hire, he said: "I don't know yet. I will correct it", added the CEO showing humility and self-awareness.
The episode also seemed to repel some of Tesla's closest backers, including alternative-energy loyalists who saw in Tesla a worthy opponent to the juggernauts of the oil and gas industries.
Others were less surprised.
Tufekci was surprised by Musk's tweet. "Bless his naive heart".
At a critical time for electric vehicle maker Tesla Inc.
"He's an inspiration to so many by virtue of some extremely clever PR over the years and needs to remember that he is a role model", Holland said. "Yes, it's not finished", Unsworth told Australian outlet Channel 7, per BBC News.
At that point, the full credit continues for a calendar quarter.
Shares were pummeled in May after Musk abruptly cut off questions from Wall Street analysts over Tesla's spending plans.