"We are all supporting Zac and see this as a positive step forward in overcoming his illness,'' Crusaders coach Todd Blackadder said. "This is ultimately about his well-being so it is important for him to take the time to fully address it.
"We are unclear on what it means for the Crusaders at this time.''
Blackadder had earlier said Crusaders management were considering whether Guildford would be dropped from the franchise for the rest of the season.
The NZRU banned Guildford for four matches after his post-World Cup exploits in Rarotonga in 2011. He missed the Crusaders' round one fixture against the Blues last season, with the rest of the suspension served during the pre-season campaign.
"It has been a challenging week for everyone involved, and we are working closely with the players' association and his manager to ensure that he gets the professional help he needs and is held accountable for his actions,'' NZRU chief executive Steve Tew said. "As people may appreciate, this is an employment matter and we must ensure that the process both respects his right to a fair hearing and our legal obligations as an employer.
"We also have a responsibility to the wider game and all those who support it. We are working hard to deliver on our obligations to the game.
"Zac's withdrawal from the Crusaders means they are able to concentrate on preparing for their 2013 season, and Zac will be free from rugby to concentrate on resolving his personal issues. We will remain in touch with Zac to monitor his progress and will address the issue of misconduct at the appropriate time.''
The NZRU are likely to take a dim view of Guildford's latest indiscretion.
"Zac has a renewed acceptance of the challenges he faces,'' New Zealand Rugby Players Association chief executive Rob Nichol said.
"We have taken the advice of experts and Zac is committed to the plan they have developed. It is fundamental that he commits fully to the plan, and sees it through. This means withdrawing from the rugby environment.
"We are all supporting Zac during what will be a challenging time. Zac himself wants to make the most of the opportunity provided and is very appreciative of the support he is receiving.''
The Zac Guildford file
* August 2011: Broke team rules when he left the All Blacks' hotel to go out after their Bledisloe Cup victory against Australia at Eden Park. Within weeks, he drank heavily and broke the team curfew after the All Blacks' 25-20 defeat to the Wallabies.
*September 2011: Guildford admitted to having issues with alcohol and promised he would get problem under control.
*November 2011: The 23-year-old was arrested after he stormed into Trader Jacks in Rarotonga naked and allegedly punched two men. He then announced a self-imposed 12-month drinking ban, saying: "I need to sort myself out.''
*November 2012: After being photographed drinking at a function, Guildford said he had changed his ways and now trusted himself to enjoy one or two drinks with friends.
