Wikipedia states that “A kibbutz (Hebrew: קִבּוּץ / קיבוץ, lit. “gathering, clustering”; plural kibbutzim) is a collective community in Israel that was traditionally based on agriculture.” A Kibbutz Salad would be a salad made from all the agricultural products built by the kibbutz community. It’s very similar to a farmer’s collective today and a farmer’s collective salad would be a salad made from the crops of the various farmers.
Obviously, when we think of Israel, we think of heat. Citrus fruit is the main agricultural export. This explains why the kibbutz salad is presented in a grapefruit bowl. I served this on Christmas eve and it was a lovely crunchy concoction.