Citation needed. But I don't suggest putting too much stock in what he says. For instance, he calls himself, as you call him, founder, yet by any reasonable measure he co-founded it with Larry Sanger. But neither holds much more than a historical role in Wikipedia now; Wales lost the elevated rights he had in the backlash to him mass-deleting images, and Sanger was banned quite recently after canvassing on twitter.
I couldn't see anything supporting your claim in the text, and to see the actual interview I apparently need to accept some cookies. Oh well, I'll take your word for it. I don't think it's unreasonable to expect people to provide sources for their claims when asked.