If Iran exports weapons to Lebanon and its BAD, why does lebanese government allow it?

Hezballah is the one that gets weapons from Iran. And Hezbullah is a legal resistance movement that has 12 MPS in the government. So they simply just can't tell to a political party to not have weapons. And plus that Hezballah is the strongest movement in Lebanon so they can't say no to it and if they did then a new civil war would happen.