I don't feel the OP is being greedy.
Airlines offer compensation to make people happy and leave them with a good taste. The OP is simply asking for any help getting whatever compensation the airline offers.
In addition, while the whole story wasn't spelled out, what was, was that the OP's brother BOARDED THE PLANE, and then was informed of the flight cancellation. I would EXPECT to be compensated for any additional cost straight off the bat (most of my food bill and hotel).
Then there are two other issues that ElAl should have to/want to deal with: they messed up and should compensate the customer "to make it right" (think free overnight shipping when a company messes up an order), and also they might want to keep the customer happy, and as a gratuity extend something.
It sounds to me like a flight to Europe is the middle level of "we messed up, and we owe you compensation", and the OP wants the last one of "we want to keep you as a customer".