Vern Unsworth, who triggered Musk’s Sunday outburst when he said Friday that the Tesla chief could “stick his submarine where it hurts,” has indicated that he may take legal action over the defamation.

Musk has always maintained that he offered the “submarine”—a modified SpaceX Falcon rocket part—in good faith, rather than as an act of self-promotion, and that the rescue team had initially supported the scheme.

Late Tuesday night—after his erratic behavior apparently contributed to a 4% drop in Tesla’s share price—Musk said on Twitter that his “words were spoken in anger after Mr. Unsworth said several untruths.”

“Nonetheless, his actions against me do not justify my actions against him, and for that I apologize to Mr. Unsworth and to the companies I represent as leader,” Musk added. “The fault is mine and mine alone.”

Nonetheless, his actions against me do not justify my actions against him, and for that I apologize to Mr. Unsworth and to the companies I represent as leader. The fault is mine and mine alone.

— Elon Musk (@elonmusk) July 18, 2018

In his now-deleted attack on Unsworth, Musk insinuated that it was suspect for a retired British man to be living in Thailand, a country sometimes stereotyped for underaged prostitution. He referred to Unsworth as “pedo guy.”

Unsworth has years of experience exploring the Tham Luang cave system, where the boys and their soccer coach were stranded, and the spelunker provided his knowledge to the rescuers.

After the rescuers successfully retrieved everyone, without using Musk’s cylinder, Unsworth told journalists that the submarine was a “PR stunt” that was entirely unsuitable for navigating the narrow, twisted cave system.

“It just had absolutely no chance of working. He had no conception of what the cave passage was like,” he said.