Gorgeous bike there. I looked at the link and there are some great detail pics. Some day I hope to find a chrome bike similar to that one. OK, I'm going to go way out on a limb with my answer, but it seems to be somewhat common sense. On many track bikes you will see the saddle pushed way forward and sometimes the seat post backwards in order to encourage the saddle forward a little more. In that condition, it would seem that the front of the saddle might be prone to drooping and the support does just what it looks like, supports the nose of the saddle so that it doesn't dip down toward the top tube when you lean way down in the drops.
That's my guess anyway!