After only their first test, which was like a 0.5-2kt yield, I can understand this claim somewhat. They could have faked that as a bluff with lots of conventional explosives. Doesn't make so much sense why they would, but it was a plausible interpretation I guess.
Given that their later tests were something like a hundred times that, it's kinda absurd to still try to make the claim
"Self-driving cars are the key to a post-scarcity future!" (when asked how the fuck that conclusion was drawn, I was told "do the research.")