The verbal sparring match unfolded last summer after the underwater rescue of youth football players trapped in a Thailand cave.
A federal court judge in Los Angeles set an October 22 trial date in a Friday court filing that rejected Musk's attempt to dismiss a defamation lawsuit filed by British diver Vernon Unsworth. Additional emails from Musk to Buzzfeed allegedly involved the business magnate saying Unsworth-who was instrumental in the retrieval of a Thai youth soccer team who almost drowned in a cave-had moved to Southeast Asia to take a 12-year-old "child bride".
He said he became a target for Musk after saying on CNN that a mini-submarine offered for the rescue by Musk from his company SpaceX, where he is also chief executive, was a "PR stunt" and that Musk could "stick his submarine where it hurts".
Musk's request to disregard the defamation suit was ultimately denied, likely due in part to an email he reportedly sent to Buzzfeed which reiterated his statements about Unsworth, supposedly calling him a "child rapist".
In seeking a dismissal, Musk's lawyers said such comments were "imaginative" or "over-the-top" insults that constituted protected opinion under the US First Amendment.
Mr Musk's lawyers argued that because his statement was made on Twitter, it was protected opinion under the US First Amendment and declared that "the public knew from the outset that Musk's insults were not meant to be statements of fact".
Taken together, they allowed Judge Wilson to conclude "There is nothing about the context in which [Musk] made the statements.that would create doubt as to whether [Musk's] statements implied assertions of objective fact".