"He was the guy who effectively mapped most of that cave", he told AFP.
Representatives for both Tesla and SpaceX did not immediately respond to requests for comment.
He was involved in the rescue for the whole 17 days.
Musk megafans - who are a particularly wonderful genre of angry online dude - argue that the billionaire should not be criticised for attempting to help, even though his efforts ended up being pretty neutral in the actual rescue.
When challenged by a Twitter user about the allegation levelled against Unsworth, Musk replied "Bet ya a signed dollar it's true".
"He can stick his submarine where it hurts", Mr Unsworth told CNN on Saturday.
In a freaky series of tweets on Sunday, Musk said he would produce a video proving his submarine would have been able to reach the children and in a comment directed at Unsworth, added: "Sorry pedo guy, you really did ask for it". "The submarine I believe was about 5 feet, 6 inches long, rigid, so it wouldn't have gone round corners or round any obstacles", Unsworth said.
Calling Unsworth "sus" - or, suspicious - was just the tip of the iceberg.
"It wouldn't have made the first 50 metres into the cave from the dive start point".
However, Unsworth also added that while Musk and his team entered the cave to assist with the operation, they were asked very quickly to leave. That said, accusing the diver that found 13 people trapped in a cave and worked to save them for over two weeks of being a pedophile-just for having the temerity to criticise his unused submarine-could be safely called a new low. The mission commander, Narongsak Osotthanakorn, said at one point that the submarine "doesn't fit with our mission", according to the BBC.
One journalist, a senior correspondent for Vanity Fair, tweeted that he cancelled his Tesla order over Musk's donation.
Generally confused, some Twitter followers guessed that Musk was dubiously linking Unsworth (who has been mapping the Tham Luang caves for a decade) with Thailand's epidemic of child sex tourism.