Johnathan Thurston had made up his mind in February to walk out on the NRL and earn twice what he had been offered by North Queensland in French rugby union.

On the table was a massive deal from Biarritz, the club former Brisbane star Karmichael Hunt had joined before his switch to AFL.

"In February when we sat down he said we should just take it and his decision was to move," Thurston's manager Sam Ayoub told reporters on Tuesday.

"It shook me a little but the gap was so great at that stage so it made me realise I had to do a lot more work in a sense to ensure that we tried to keep him in the NRL."

Ayoub said the Test halfback, rated by many as the best league player in the world, could have earned double anything the NRL had come up with.

"At that stage definitely," Ayoub said.

"Before anybody talks about greed, he's no different to any one of you people, myself or anybody else.

"If the opportunities are there you owe it to yourself and your family to look at those options and go from there."

Thurston, who also had four NRL clubs waiting in the wings to table offers, was eventually convinced to sign a three-year extension by third party sponsors bumping the deal up to a reported $2 million.

"It's sort of like a business now," the 27-year-old said.

"The way I treated it, if the money was substantially a lot better (in union) and I was guaranteed to have a bit more of a life after footy, then I would have really considered it.

"It was mainly just all money-based and that was certainly a lot higher than what I could get here.

"But the advice that I've been given from my manager and close friends is to stay in rugby league and certainly life after football, I'll be able to explore more options there."

Ayoub said those options would be possible because Thurston would forever be identified with the 13-man game.

"At the end of the day if he packs his bags and heads overseas, he comes back, the game doesn't have ownership of him, nothing has ownership of him," Ayoub said.

"But, by staying in the NRL, I think at the end of the day the game will have some ownership and reward him in other ways."

Ayoub said that included opportunities with the independent commission which will eventually run the NRL, and the setting up of Thurston's own foundation to benefit indigenous communities.

"We've spoken to some major companies and corporations who are prepared to get behind it and at this stage hopefully some government bodies as well," Ayoub said.

Thurston, who has played 15 State of Origin games for Queensland and 16 Tests, said the chance to win a premiership with the Cowboys was also a factor.

"If that happens and I happen to be the captain when it happens, no one can take that way from me so it certainly did weigh in my decision," he said.

"I wouldn't have re-signed if I didn't think we have the players to win a comp and the coaching staff."

The Cowboys will now turn their attention to a host of off-contract stars, including former Kangaroos Willie Mason and Luke O'Donnell.

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