This is a board my friend, who sat North, asked me to judge. I agree that it is a mess from the very beginning, since I would open 1♣. But I think 1♠ and 2♥ were not the worst. While my friend insisted that his pd was to blame for the entire mess, I said he was partially responsible. I could accept 3NT bid since it might be the last chance to bid 3NT, given that two majors were "misfit" (pd didn't show support for ♠ and South was void in ♥). 4♦ was still OK as North wanted to investigate slam but not sure which level would be good. South might think 4♦ showed slam interest in ♥ (as Justin also mentioned the same), and therefore tried to show and ♣ fit. So I think 5NT was the worst (pick a slam), because South was completely in dark. I would bid 6♠ instead of 5NT.