One opening move can’t possibly confirm cheating since the opening moves played by the best chess engines are also the same moves played by the vast majority of human players.
But if there is no obviously desirable move, and instead a wide array of potential equally good moves, then picking the same as the computer picked gives a high probability of cheating. That being said, I find it unlikely that that's the case here.
In case of the first moves, there's definitely not a wide array of potentially equally good moves. There's a very well known set which is studied by every serious chess player.