The WC calendar was set before the draw took place. So there was no chance of them knowing who they will get even though probability was there for Iran or Saudi landing there. I think it has to do with logistics of the games and I highly doubt they will fast at this big of an occasion unless really kos khol.
He didn't actually say they were fasting. It stated in the article which is wrong. I do remember we ended up playing big tournaments during Ramadan before and I do remember the players said due to the nature of their work/sport, they could not fast. It would be dangerous for their health.