“Nasrallah and ISIS both are ememies of Israel and both are on or near the Golan.”
Some enemies are more enemies than others. Israel clearly fears the more organized Perso-Russian-Secular-Shittes than they fear barbaric horde of 7th century Arabo-Sunni-Turko-ISIS camel fkers.
Israel fears the modern arms and airpower Russia is using on various moderate groups along the Golan. Al Quds brigades may be setting up firing positions along the border, to be supplied with those same modern arms.