Besides, I don't see why ORD is so important for El Al. They already have 4 destinations on the east coast and 2 on the west coast in addition to YYZ. That's plenty of options for connections. It's not like they have a hub there. UA has much more to gain from it in terms of connections because they don't have nearly as many connection options as El Al. El Al partners with WS, PT, AA, B6 and VX and that gets them pretty much everywhere.
If it's just to provide nonstop for the Jewish community in ORD, perhaps they should be adding YUL too....