MC & Visa do business with thousands (millions?) of adult shops in the US. They have no moral compass or concerns about being involved in financial transactions with porn purveyors.

They do have a tremendous aversion to people involved in criminal activity or at high risk of doing so. Once PH started publicly flirting with that threshold they got dumped.

The morality police are the police.

It's a different scope. Porn shops sell product in one place and local authorities deal with that. A bigger entity with interstate impact is a federal matter and penalties are much more severe.