So it's either a firmware bug or a bug in the "info" portion of the menu there.
I expect it's neither, but functioning as designed. The footnote on p.128 of the manual indicates that if a correct exposure cannot be obtained at the max ISO of the selected range, a shutter speed lower than the chosen minimum will be used. So, it seems to be intended as a 'soft' limit.
As pointed out above, for the 'min shutter speed in Auto ISO' available on the 5DIII, the 1D X has that setting, but also has 'hard' limits (lower and upper) that can be applied to shutter speed and aperture, which the camera will not override to get a correct exposure.
So, if you absolutely require a min shutter speed on the 5DIII, your best bet is probably to set the max allowable ISO at the top (or use Tv or M mode).