I wouldn't go so far as to say he was lying about the species of gecko. Turner's geckos are very similar to Bibron's in appearance and there is some thought that because Turner's overlap into Bibron's range (and not the other way around), importers have been shipping them, mistakenly, as Bibron's. Bibron's are not CITES protected but they are from South Africa and like countries like Oman, export is illegal but if the geckos had somehow travelled to a legal area, they could be collected. I think he is young and is less willing to accept that what he has are not Bibron's. It makes little difference to me since he is caring for them as Turner's. All the online literature that explains Bibrons' care is actually about Turner's gecko. I have a feeling he knows what he has aren't Bibron's and that he is trying to save face. Why else would he accept 15 geckos that may never breed with his?
Honestly, my mind says cut the deal loose and find another buyer. My heart says I shouldn't cut him off just because he is 13. At 13 even I stretched the truth now and then.