Jimmy Wales has been poked at with the question of whether he should call himself a founder or specifically co-founder for a long time, by right-wingers who think Wikipedia is too woke, and want to irritate and discredit him as much as possible, and instead raise up his co-founder Larry Sanger. Sanger has right-wing views and a habit of accusing any article as biased that doesn't praise Trump and fundamentalist Christian values, and takes these as proof that Wikipedia has a left lean.
The interview Wales walked out of was for his book tour. I imagine it's the umpteenth interview that week with the same question asked for the same transparently bad-faith reasons, trying to bend the interview away from his book and into right-wing conspiracy theory land.