He's using it as a filter layer for his substrate. I'm not positive, but i think the activated carbon and charcoal are different. And i don't know if it'll help since i don't know your area, but i found some ground charcoal at Pikes for orchids and used that.
I went to Repticon when it came here this past weekend. There weren't a lot of Chams mostly snakes, beardies, and geckos. I did see some baby veileds, a couple of Jackon's, and one Chamaeleo quadricornis that wasn't for sale just display. At the show i asked a couple of vendors and they said you...
You may not watch the actual tumor being removed, but you do see the symptoms and probably the doctor visits, x-rays, etc... If no one ever saw it, no one would believe it. There is a walk to cure cancer because people watched others suffer and die from it. And if they hadn't seen it first hand...
I wouldn't use pressure treated wood it's treated with toxic chemicals (amine copper quat (ACQ) and copper azone (CA)) to protect it from rotting and insects. So i wouldn't think this would be good for a cham either.