You know the reason...Dr. Sanjay Gupta. The narrative does not survive the questioning. CNN had to do damage control after Gupta's appearance. In fairness, the Rogan show is a grind and gives a lot of time to be made foolish of (same critique was levelled on this forum against Jordan Peterson after all). It's a long time to stay focused and not all of it is going to be gems.
Rogan has said he invited Dr. Fauci to appear. Given Rogan's antivax following, you'd think Dr. Fauci would welcome the opportunity to directly appeal to the antivaxxers and bring them into the light. Of course Dr. Fauci is busy fighting the pandemic, but given the chance to change minds, you'd wonder why Dr. Fauci wouldn't go on?