If your referring to leachies, It's locality and subspecies crossing he advocates.
From what I understand the Leachianus henkeli subspecies status has been dropped and therefore not really advocating hybridization at all. The only reason he does advocate crossing localities is because of the limited numbers of specimens exported. Claiming to be knowledgeable on population genetics, I would think you would understand the reasoning behind it.
In your post earlier you said something about using hormone treatments to flood the market with weak froglets. You should know when they first bred joazeirensis they did it without hormones. Please don't take any offense to this Tony.