IMHO.
for the years I have spent in this region my personal policy has been. If my F/O is fasting thats fine with me and i don't have a problem with it, not that i think it's a good idea. In the end he becomes a flap and gear operator while fasting, nothing more nothing less. Bad luck for him is both sectors are in day light. Having said that, I have never / rarely operated short haul flights and multi sector flights in this region so I cannot speak for those who do.