Mäki clearly and blatantly obstructed Bolshunov. The course design gave him the opportunity to do so, because he could sweep around that final corner forcing Bolshunov to go the long way round (which he did) and then make a beeline for the right-hand lane as long as Bolshunov couldn't accelerate so hard around the outside of the final corner that he passed Mäki (which would be nigh on impossible), and to make it into his 'chosen' lane (which would in most cases be the most disadvantageous, as the distance is longest) before the lanes are marked means having to swing very wide quite dramatically which exaggerates the swing from one side to the other and makes it more of a cutting-off move (this is also one of the reasons I'm against marked 'lanes' in sprints in cycling, as it will just move the problem back to the lane entries rather than the line, and if somebody is fighting to find a space, they have less time to get to the lane they're after and will therefore have to either accept a minor position behind another sprinter or veer wildly to find an unoccupied lane). So while he has plausible deniability, it's clearly a move which is designed with obstruction in mind. At the same time, he did succeed in making it to the right hand lane before the markers, which means the move is not illegal (ironically, if he did it less dramatically and more safely, it would have been obstruction!).
As a thought, if I recall correctly the Biathlon World Cup spent a few years in Lahti in the mid 2000s, and because of the needs of biathlon, the athletes had to come clockwise through the stadium, so the range was opposite the crowd. As a result, the athletes would arrive in the stadium on the side the XC finish is, and travel in the opposite direction to the XC, with the finish at the opposite end of the athletics stadium (so at the start of the 100m, not the finish, in athletics configuration). This is probably hard to achieve without a temporary bridge either into or out of the stadium in XC, because obviously the biathletes will stop for a while in the stadium to shoot rather than looping back on themselves immediately, but that 180º corner and short run to the line seems to be proving increasingly problematic in Lahti in recent years. At least no sprint competitions were scheduled there this year, I recall some demolition derbies going on in icy conditions a couple of years ago.