The linked article seems to indicate that this man was ordained by a New Rite bishop since he was part of a group established--at later suppressed--by a Conciliar bishop, thus his orders are, at best, doubtful. Why would any traditional Catholic priest have anything to do with him whether or not he knew anything about his other problems?
A few years ago Fr. Pfeiffer said in a sermon that probably most Novus Ordo Masses are valid. Which implies he doesn't have much if any doubt about validity of New Rite priests. This is a difference I've noticed between him & Fr. Zendejas, because Fr. Z has made comments regarding the doubtfulness, and how/why the SSPX used to conditionally ordain.