de Grandhomme Opts for New Zealand

It seems former Zim U19 player Colin de Grandhomme has opted to take his services overseas, after New Zealand provincial side Auckland asked the ICC for clearance to sign de Grandhomme as a local player. According to Auckland coach Mark O'Donnell:

"[de Grandhomme]'s making New Zealand his home, has declared he wants to play for New Zealand and it's just a question of how representing Zimbabwe affects him."

If the ICC decide de Grandhomme is considered an overseas player, he wouldn't be eligible to be contracted by Auckland. If I understand the rules correctly, since de Grandhomme has represented a Full Member nation at U19 level, he should have to complete a 4-year residency period before qualifying for another country - which by my reckoning should leave him as an overseas player for another few years yet. The ICC get the final say, however - but either way, another promising young player has been lost to Zimbabwe.
New Zealand Herald - Auckland check out Zimbabwean's eligibility