I guess that's just my personal incredulity fallacy & it's not really based on the face that his physique can store more toxins than ours.

I mean have you seen Roms physique? he looks like a legit 30% and he's been on the primal diet for 8 years!

Detox is short for detoxification, which is when your body is getting rid of toxins. As you will know toxins are stored in the fat. This is exactly why raw butter is so important on the diet. On top of it being so nutrisous, and so dense in energy, the most overlooked aspect of it is that its a fat source without toxins. Bone marrow and other animal fats are extremly nutrisous aswell, but thats where the toxins are stored, so you risk getting sick if you eat them unless they are cooked or your body is well adapted. Just like animals store toxins in their fat, we humans store toxins in our fat, so the more fat you carry on you, the better your body can handle the detoxification and just be more secure in general.

One more thing I want to add, again I will assume that you are still developing just like me and hopefully working out aswell. In that case, take this opportunity to put on some fat, not to the point where it destroys your hormones, but enough so that you can go on a generational bulk, gain a lot of muscle, and handle the detox well.
Detoxing and building a great physique both take years to complete. So say you build a lot of muscle, and the detox is approaching its end as your body is getting more adapted to the diet, that should be the time to cut down a bit on the bodyfat. That way you will have spent say 4-5 years extremely productively from a physical perspective, and hit two birds with one stone. That is what I would call a proper body transformation.