Sources close to Williams also asked if an "agenda" was behind the his exclusion from Tri-Nations test between the All Blacks and the Wallabies in Brisbane tonight, the New Zealand Herald reported.
The newspaper said prolonged contract negotiations between Williams and the New Zealand Rugby Union (NZRU) had already raised eyebrows.
South Pacific Brands yesterday said it had been negotiating with Sonny Bill Williams and his manager Khoder Nasser for him to endorse its Pure Energy brand.
However, company director Steve Shaw said the NZRU had suggested Coca-Cola was threatening to "significantly reduce its sponsorship" if Williams endorsed Pure Energy.
He said Pure Energy was "a perfect fit" and Williams could net "some very substantial sponsorship fees."
Williams had repeatedly said he would sign with the NZRU for another year. The Blues and Chiefs were also competing to sign him for the Super rugby series.
All Blacks coach Graham Henry said he was surprised at how long negotiations had dragged on.
Mr Shaw said it was hypocrisy and the rugby union had double standards by allowing All Blacks Dan Carter and Richie McCaw to endorse a water brand that competed with Coca-Cola's Pump water.
NZRU commercial manager Paul Dalton said the objection to the endorsement was an "employment matter". He said the NZRU did object to a proposed personal promotion for Williams and was working "on facilitating other opportunities for him."
Williams' close confidante, former league star and boxer, Anthony Mundine, said it was crazy Williams was not selected for tonight's Tri-Nations decider.
He said Williams was one of the best, if not the best, backs in game and there was an agenda not to select him.
