WATCH: Rick Santorum Doesn't Understand Why He's a Danger to Kids

Grosse Pointe High School students in Michigan will need their parents permission if they attend an assembly to hear Rick Santorum speak. And Santorum just can't understand why.

At first, the assembly was canceled, with the principal saying Santorum hadn't sent a copy of his speech for review. Then the principal decided to allow it so long as parents explicitly gave their kids permission to attend. Santorum told Fox News' Bill O'Reilly that the decision was "disappointing." He seemed bewildered to be treated, "As if there is something that that person could do to harm your child."

Santorum during the interview with O'Reilly went on to say that it's actually marriage equality that would be bad for children. In fact, allowing same-sex marriage stops kids from being born, he argued. "The consequences are you're going to probably have less children" because, he said, marriage is for procreation. "It's happening, as we, it's already happening in America."

Santorum had been invited by a new chapter of Young Americans for Freedom, which Patch reports was formed in February. O'Reilly bragged that he helped pressure the school into allowing the speech, which Santorum is somehow being paid $18,000 by the group to make. For his part, O'Reilly defended Santorum as his "friend" who is being unfairly attacked. But at the same time he summed up why people may be uncomfortable with letting the man who once compared gay people to bestiality talk to high schoolers.

"It's marriage equality," O'Reilly said, explaining what his critics might say. "Whenever you see the word 'equality,' you know what they're going for. It's the rights issue. And you are seen as an opponent of gay marriage, which you are. So, therefore, if you oppose, senator, equality, you're a bigot. And we can't have bigots talking to the kids."

Watch a David Pakman segment about Santorum's interview.

Watch the complete O'Reilly Factor interview