Regarding low capacity on the JED route when BD flew direct to JED out of the big pilgrim migration the yield was low and the load factors were not great. At the moment it is Omra season so the flights to JED are busy. But out of season they can be very quite.
If BD can succeed on the TLV route where they entered a market that was already well established with BA and EL AL and a year on down the line the aircraft type has been upgraded.
I think if BD keep their game up then the RUH and JED route will stand up to BA re-entering the market.