The former All Black is aware of critics who said he should be helping out the struggling Warriors, but he said a variety of factors contributed to his move to Sydney.
"I moved to Australia when I was 14 and my wife is Australian," he told the Daily Telegraph.
"I've got four kids under five. The plan was to always set up shop in Sydney once I'm finished, not in New Zealand.
"[Roosters coach] Trent [Robinson] was the first to ring me. He had injury problems with a few of the boys.
"And apart from Trent and Nick, I think most people know I'm still close to the boys.
"The Roosters are close to my heart. If I wasn't playing I wouldn't be playing at all.
"I've been in holiday mode and travelling around Europe with my family. We'd done France and Turkey. Then we were going to do Bosnia and Greece. Then this opportunity came up."
Williams touched down in Australia early this morning, where the cross-code star and his family appeared exhausted after a long flight.
"It's good to be home, it's been a long flight," Williams told the media at Sydney Airport.
Despite the long-haul flight, Williams still managed to pose for a selfie with a Roosters fan.
The 34-year-old will now spend 14 days in mandatory quarantine before joining his team in their training bubble.
