Many of these cases are bought to highlight the boycott rather than because the passenger really wanted to travel on Kuwait Airways. There are other options available on their fifth freedom routes even though KU may have the lowest fare.
The ME3 carry Israelis and even have a Kosher meal option available, through transit at the hub is allowed though entry may be prohibited into the country.
Personally, I wouldn't want to give my business to an airline that didn't want me and was from a country that regarded my country as it's enemy. The refusal has stopped ticket sales on London - New York and must be costing them a fortune.