I too spent some time thinking through the sequence of backwards moves, shifts and turning-to-face ... but, backing up, I believe the Gordian Knot is cut by the suspension of the requirement for X to contact 1's flank front-corner-to-front-corner (being blocked from doing so by an enemy element, 2, and having contacted the *full* flank edge of 1 by moving directly forward). If X is not required to shift into the space occupied by 2, the latter is not an obstructing element.
Cheers,
Ivan.