No actually, using a polarizer in bright sun makes a lot of sense. Properly used, the polarizer will bring down the brightness of the sky (sort of) like a graduated ND filter. This makes your meter think there's less light, so it increases the exposure. This makes the shadows less dark. Bringing down the brightness of the sky is reducing contrast of the scene, and since we know how contrasty Velvia 50 is, it should allow a bit more shadow detail without completely blowing out the sky.