It doesn't matter because if the article is correct, it's on him to produce the raw data, there is no need to speculate. As it is, the story is fishy in every sense of the word and definitely warrants an investigation.
Simply using Occam's razor in the absence of better evidence. Which is on those making the claim to produce, you can't just publish papers and then go "I've done the isotopic analyses, trust me bro". Researchers could make up anything then, there needs to be accountability. At the very least his team needs to retract the paper.
Here's another possibility: During goes to DePalma to collaborate and asks if DePalma still has the data. DePalma says he doesn't. During sees this an an opportunity to claim credit for the work.
It's impossible to tell which scenario is more likely. Are you really willing to ruin someone's career over purely circumstantial evidence provided by a biased witness?
What evidence do you have that anyone has actually looked into those data? In what context? You're simply repeating his claim but there isn't evidence the data was ever scrutinized. In research you're shown other people's data all the time - that doesn't mean that people actually look into it.