He shifts position not to try to trick his Queen, because she won’t ever be fooled. Not by him.
He shifts position in hoping that, with the sudden movement, there is a chance the terrorizing vision that haunts his eyes will vanish. It has happened before.
He could simply turn his back on the vision. And face the Queen? With terror in his eyes? He can’t do that, knowing the impact it will have on her. Not tonight, with all the important consequences in the next many moons of her life.
So the King simply shifts position, his back still turned to the Queen, and endures the horrific scene laid before his eyes.
Greco Roman Sims 3 Poetry 