I don’t hold people responsible or expect apologies they don’t owe for what someone else does. Trump supporters are highly unlikely to expect him to apologize for something he didn’t say; they should expect the same from Cruz or any other candidate.
Cruz knew exactly what that PAC was doing, otherwise he would have denounced the ad, said it “had no place in the realm of political discourse” and the broad in charge of that PAC used to work for Scott Walker, and Walker fired her because she caused more problems than she was worth.
Of course it’s easier for Lyin’ Ted to play the pious and righteous holy man, what else should we expect from our new ‘Dominionist King’?
I don’t remember anyone suggesting that Cruz needs to apologize. He should, however, denounce the ad as inappropriate. The attack ad against Melania includes the words “vote for Ted Cruz on Tuesday” after all. It is an ad for Cruz, whether he was responsible for it or not, so Cruz needs to make it clear he doesn’t want ads like that made on his behalf (unless, of course, he actually does want ads like that made on his behalf...).