I tend to find that is is very common for Arab Christians to side with Muslims over Jews for various reasons. The 1980s were a “marriage of convenience” between Gemayel and Begin.
I suppose it’s easy for Preterist/Replacement Theology Christians to discount God’s people. The belief that Christians have completely supplanted the Jews and taken their inheritance is a sickness that infects many Christian denominations, even here in the US. Once you accept the notion that Jews are no longer God’s chosen people, you can excuse a lot.