If what's written on the blog is true, the interviewee knows their stuff technically and the interviewers were just bad: they wanted to check some boxes, feel good about themselves and be done. Nonetheless, by self admission the interviewee also didn't speak English very well ("This was my first interview for a foreign company and the first time in life I spoke english") and that could also be part of the problem or something we didn't know is how the overall communication went, this might have played a part in the rejection. A candidate, but also an employee, might be very strong technically, but they should be able to clearly communicate their solutions and play well within a team, having a genius Anarchist might not always be the best. Anyway, from the post, I'd have moved forward with the candidate and if they were rejected they probably dodged a bullet. Best of luck with the next interviews!