That cautious approach to his return from concussion proved to be right, but the presence of Jerome Kaino in the squad means the news delivered to him at the team's central Auckland hotel wouldn't have been as crushing as it might have been.
Six months ago, when Kaino was playing club rugby in Japan, it might have been a different story. The All Blacks would probably have had a reshuffle and put Liam Messam to the back of the scrum, giving the inexperienced Steven Luatua the No6 jersey.
Another option would have been for Richie McCaw to start at No8, with Sam Cane playing openside.
Long-term, probably only the inexperienced Luke Whitelock was next in the pecking order behind Read.
Now, with the return of the World Cup-winning Kaino, a 31-year-old veteran of 48 tests and nearing his form of old for the Blues, Hansen has a ready-made replacement.
To a slightly lesser extent, the return to form of Victor Vito, who has been outstanding for the Hurricanes, will also give Hansen comfort.
At the end of last year, Vito had been tried and discarded once again. Now he has forced his way back and is a serious contender.
Read trained with the squad yesterday, which suggests his symptoms are not overly serious. But his return for the Crusaders after suffering the injury, caused by a high tackle against the Chiefs in mid-April, took a long time - five weeks.
Hansen appeared confident his latest symptoms would only rule him out of Saturday's first test against England at Eden Park, but in truth there is no telling how long it will take Read to come right.
Hansen broke the news yesterday after revealing flanker Cane was withdrawing from the series with a knee fracture and wing Julian Savea was in doubt, also because of a knee.
"He's frustrated, as you would be, but we're very lucky that we've got very capable people who can fill in in his place and JK and Victor have been performing very well," Hansen said of Read.
Asked if he was concerned about Read's long-term health, he said: "We've been through it before with a certain Richie McCaw. We've got really good faith in the people looking after him.
"Long term, I'm not too concerned."
Yesterday's injury bulletin will probably be a boost for a below-strength England team, but the depth in the All Blacks suggests the home side shouldn't be unduly troubled.
Crusader Matt Todd has recovered from his recent calf problem and has joined the squad for Cane, and is a possibility to cover for McCaw on the reserves bench.
Cory Jane will be in line to start on the left wing if Savea is ruled out, and Luatua has been added as cover for Read.
