From the news article to which you gave a link I understand that one way or the other, all passengers have to go into quarantine after arrival in Israel:
"Passengers on an El Al flight from New York to Tel Aviv will be tested for the coronavirus on the plane itself or before boarding on Thursday (Aug 5) to speed up procedures upon arrival in Israel, where infections are on the rise.
The Israeli airline announced the plan a day after Israel said travellers from the United States, like those from many other countries, would have to self-isolate for at least a week after landing at Tel Aviv's Ben-Gurion airport."
For the flight crew, it would of course be better if only passengers with a negative test certificate were allowed to check in for the flight.