Two amateur chess players guessed the best sequences of WBBWW and then plugged the result of their guesses into an engine to statically analyse the position. There is absolutely no chance that they found the best options for either player.
The sequencing argument that they make has no real foundation. Introducing double moves could have all kinds of side-effects which they later mention when showing their guesswork-variations but skip over when trying to make the previous "logical" argument.
The only semi-useful sentence in this paper is the following:
> More light would be shed on this question if the two leading machine-learning chess programs, AlphaZero and Leela Chess Zero, were taught to play with our proposed change in the order of the 3rd and 4th moves from White-Black to Black-White.
The rest can be summarised as "We thought of this potential rule change and it seemed to us to be more even for black."
If they had wanted to then there are only around 10,000,000 possible game-states after the first WBBWW and potentially looking at computer evaluations of the whole tree of possibilities could be semi-interesting and definitely very achievable. Probably better and easier to guess instead though to be fair.