Why would Tameifuna - a guy who was born in Auckland - choosing to have another go playing for the All Blacks - be unfair to Tonga?
As we have seen with many Tongan/Samoan/Fijian players, the myth that their contracts are in danger if they are selected for a PI team, is garbage. The NZRU don't count them with any foreign player restriction. Mahonri Schwalger, Jack Lam, Alapati Leiua, Asaeli Tikoirotuma, TJ Ioane, Ahsee Tuala etc, etc, etc all had NZ contracts in the last two years. Many players such as Leiua, Lam, Tikoirotuma get better offers from English, French and Japanese clubs, and without the possibility of being selected for the All Blacks choose to leave to earn more money. Tonga and Samoa already benefit from NZ player system, so I'd hardly call not being able to select players that your union had nothing to do with developing, as unfair.