Oh yes, it is mentioned on the thingiverse page but rotate_extrude with an angle is only supported in 2016 and above versions of OpenSCAD (I got 2017.01.20 specifically for this feature). Otherwise it just does the full 360 degree rotate like you see. I grabbed the snapshot they have on their download page and that's what I use to build the model. Alternatively, one could do an intersection of the rotate extrude and a cube of diameter x radius.