For all the bashing about twitter, in the not-too-distant past this exchange would have played out over a year or so, assuming the original claim didn't just languish in some obscure journal somewhere.
Well, that's the big issue isn't it? Pre-twitter, pre-out of control social media, etc a claim from a Jr level person like this would have been met with skepticism and gone through an academic filter that would has squashed it. Nowadays its all over the world before there's a sane response to it. Sadly, many who have memorized this little factoid will never see the rebuttal.
It's hard to tell how much filter was applied since the BBC article only cites the team themselves- I don't see any indication that Larsson is a 'Jr level person' in their field. This could have easily have been published in a specialized journal and not have been refuted until someone with the right background came across it.
I guess in American universities, "researcher" is only an early career position. Later, you either get a professorship, or they kick you out. But this case is about a Swedish university, and there people can be "researchers" their whole careers.