The Olympics are supposed to represent international goodwill. If the Iranian athletes refuse to exercise that goodwill, they are violating the spirit of the games. On the other hand, the matter is as simple as allowing the Iranians to forfeit any matches against Israelis; a ban at this juncture would mess up the scheduling that has already taken place. This is a tough measure, but it's the only FAIR solution. In my mind, it isn't about anti semitism, but about goodwill, or the lack thereof.