This *could* turn out to be a good thing for Lois . . . . She already stood up to Lex as far as having the guts to get up and walk out; rescuing Jon and Clark from his clutches and putting and end to his ability to threaten them/her should go a long way toward helping her heal.
Personally I wouldn't hesitate to use deadly force if someone were threatening me/my children. Lex Luthor is not your average burgler; there is absolutely no chance here that he'll go away and leave the family unharmed if they just cooperate. He is prepared to use deadly force & therefore Lois would be justified in using the same level of force in self/family defense.
