The hooker was set to undergo self-isolation in a government facility for a fortnight but the Warriors leadership group decided he should instead join the team.
The Warriors have been impressed by the high standard of the facilities and training venue of Scully Park, which neighbours a hotel that they have all to themselves.
Assistant coach Tony Iro said Roache’s wellbeing played a big part in the decision.
“The team was quite happy to do that. Firstly because it gives Nathaniel the opportunity not to be in isolation by himself,” Iro told Newstalk ZB. “We’re very happy to stay here an extra four days given the security of the players, given the facilities and how we want to keep as safe as possible.
“We feel really privileged in the current climate that we’ve got access to a place that keeps us safe, keeps people around us safe and gives us the best opportunity to prepare.
“I honestly feel like we’re probably one of the safest groups of people in Australasia.”
Roache has undergone NRL biosecurity protocols and will be eased into the training process, which the rest of the squad began on Tuesday.
Roache missed the original flight as a precaution after showing flu-like symptoms on their morning of their departure.
It means outside back David Fusitu’a is the only Warriors squad member not in Tamworth, having asked to remain in Auckland for personal reasons.
Fusitu’a isn’t expected to travel for about a week, meaning he’ll undergo self- isolation and will miss at least the first game, and potentially more depending on his fitness.