Sometimes you bomb them so you don’t have to, or to block a means of egress. Either way it’s a legitimate military objective that justifies civilian casualties.
People could just leave the area, though. It’s not like Israel doesn’t tell them about the strike.
Their father has a choice. He should act in a way that’s in his children’s best interests but if he thinks attacking Israel is more important, then the consequences will be his to live with.
I agree with you it would be better if he were simply killed, though; that’s certainly the position Israel takes on the matter.