That's the trouble with a democracy. People can have their own beliefs and get away with it. Of course Israel is not a true democracy. Israel has laws available to strike at any citizens who annoy the rulung right wing Jewish regime. If they don't have the specific law they need they can make one in short order and make it retroactive.
12 Iraqi troops, militiamen killed in multiple ISIS suicide attacks (AP)
from the article: Israeli Arab MKs assailed for attending Hamas-Fatah reconciliation