"Jerome Kaino from the Blues was granted some leniency in that regard and we've done it for others. We looked at Charles and while he is a well-known player he has played only three or four full seasons of Super Rugby anyway and he doesn't trigger our policy. He cannot stay for the full campaign."
Asked if the decision was "mean-spirited" or "heavy-handed", Tew said: "We're in charge of one of the most precious gems in New Zealand society - we don't play cheap shots or make knee-jerk reactions.
"On balance we've said look, Charles is committed to another future for the next three years, he's not playing in New Zealand for a very long period of time and we're better to get on without him and let some other player have that jersey and develop themselves in this country and not set a precedent we wouldn't want to live with, frankly, because in our view we've got to look after the integrity of our competition and our policy of rewarding players who stay and play in New Zealand."
Asked about how that policy applied to the likes of Nemani Nadolo, a Fijian not available for an ITM Cup side or a New Zealand representative team and who has joined the Crusaders from Japan late for two seasons running, Tew said: "It's been weighed up, hasn't it? We've provided a little bit of flexibility in that case. He is available for a significant chunk of the campaign and particularly the business end and that is where most teams will tell you it's important to have continuity and depth.
"Losing one of your best players with two or three key weeks of your round-robin to go - it's not the case for the Blues now - but the other four New Zealand teams - this is it.... you don't wnt someone who has been taking up a jersey walking out at this part of the year. We treat every case on its merits and it's not about Charles' decision, it's about his unavailability to New Zealand rugby for the next three years. He's made that call, that is the reality."
Blues chief executive Michael Redman said yesterday the franchise would prefer to have Piutau for 11 matches rather than none.