It's true bro, I know him personally and I can tell you that he didn't lie, he was only running 6/7 times a week when he won at Samorin u23 european xc. He's extremly talented bro, he doesn't need a lot of mileage to be good, so if he can build up his mileage to 100 one day, he'll be even faster !
He is doing 80mpw right now. That's what that Instagram story tells me. You can't count race weeks and weeks where you are cutting mileage to peak, or a rest week! Ridiculous.