But he's wrong on his most central point. Let me quote wikipedia:

In the United States, laws vary from state to state. As of 2012, adultery remains a criminal offense in 23 states.[54]In those states where adultery is still on the statute books (although rarely prosecuted), penalties vary from life sentence (Michigan)[55] to a $10 fine (Maryland) to a Class B misdemeanor (New York)[56] to a Class I felony (Wisconsin).[57] In the state of South Carolina, the criminal fine for adultery is a fine no greater than $500 and/or imprisonment for no more than one year [South Carolina code 16-15-60], yet the divorce laws codified at South Carolina Code Section 20-3-60(A) deny alimony to the adulterous spouse, which in some cases can cost the adulterous spouse millions of dollars in future income.[58] Other states where adultery is illegal include Massachusetts, Idaho, Oklahoma.[59] Massachusetts, Idaho, Michigan, Oklahoma and Wisconsin are the only states to consider adultery a felony. In the other states it is a misdemeanor.