He’s heard his opposite camp. He just says what he finds to be correct. I remember when he was a nose-to-tail carnivore who would judge his guests for not eating full carnivore or having had pizza for some days. Now he’s found a new dogma to stick to: the fruit diet. 

 Looks like he's going after the wrong thing (diet), might be something deeper to look into. Sadly he's dragging others along for the ride. 

 Indeed! Just because of the “flexibility” fruits might offer, many people follow his advice and fall into a trap.