This seems like an OK strategy to me, although in my experience chips are flung at the sides of the rails and screws, not the top. You could angle it, but then you wouldn’t get top coverage.
To me, the lower X axis rail actually seems like a better candidate for this kind of unidirectional shield, since the X screw and top rail are occluded by the gantry beam, and rarely see debris.
I made some progress on accordion covers for my Y axis here, btw: