Not overly surprising, really: Beitar Jerusalem's fans, and La Familia in particular, were quite proud of the fact that the team was the only one in the Israeli Premier League never to have had an Arab player. The supporters are Orthodox Jews, and tend to be among the crazier of the Orthodox Jews. The team's often been sanctioned for their fans' actions and La Familia in particular chants anti-Arab and anti-Muslim slogans.
Also, when the two players were signed, the team's offices were torched not long after.