The NRL has a rule that bars players from holding simultaneous contracts with both one of their clubs and another franchise, meaning Williams would potentially have to terminate his reported two-year $10 million contract with the Wolfpack – as the NRL does not have a loan arrangement deal with Super League clubs.
While Wolfpack owner David Argyle says he would be prepared to rip up the lucrative contract and sign a new deal for 2021 to create a loophole for Williams, it would leave his club in a vulnerable position.
The Roosters meanwhile have just $A200,000 remaining in their salary cap with which to sign the $5 million dollar-a-year man, so the club would need to get Williams at a heavily discounted price; which could also come under scrutiny due to the NRL's own laws.
Any NRL contract must reflect what the governing body determines to be a player's market value - the same law foiled the Parramatta Eels' plan to sign Israel Folau out of AFL in 2012 - an amount determined by the league's salary cap auditor.
The Sydney Morning Herald believes that amount will be set at a fraction of his going price in Super League, just $A400,000, which will allow Williams to fit under the Roosters' cap if it takes into account the small part of the season he will actually play.
On top of contractual concerns, there are major logistical pressures to overcome before Williams' can take the field for any NRL club.
Firstly, Williams needs to get into Australia where he will require approval from the Australian Border Force. While Williams' wife Alana has an Australian passport, the family would also need an exemption for the two of their four children who were born in New Zealand and the government has been stingy on approving entry for non-citizens - a fact the Warriors can attest to.
Secondly, Williams will need to spend two weeks in isolation upon entry to Australia and then find a way to get match fit for the world's most cutthroat rugby league competition.
Despite these hurdles, Roosters coach Trent Robinson is confident Williams will be playing for the Roosters in due time.
"There's a few things that need to be done to get it sorted but conversations are clear. It's just all the details that need to get sorted with how it's going to work.
"He's a Rooster and he's going to add value in some key areas."