Henry said: "We think the other three are playing better than him at the moment.
"We are sure he will play many more Tests for the All Blacks in the future."
There was also no room for openside Marty Holah, who had an outstanding game in the New Zealand Maori's victory over the Lions.
Instead the All Blacks selectors - Henry, assistant coaches Wayne Smith and Steve Hansen and Sir Brian Lochore - have opted for just one specialist openside in Richie McCaw with Holah named in the Junior All Blacks squad.
The announcement marked the return of Canterbury and Crusaders fullback Leon MacDonald to the international fold after spending the 2004 season in Japan playing rugby.
MacDonald and Aaron Mauger will be used as back-up fly-halves to Daniel Carter, meaning there is no room in the squad for veteran Andrew Mehrtens, who could have played his final game the All Blacks.
New Zealand Maori captain Jono Gibbes and hooker Derren Witcombe will also train with the squad.
Witcombe is there as cover for Anton Oliver, who is still recovering from a calf injury, while Gibbes is struggling with a foot injury but is likely to remain with the group if that heals.
New Zealand squad: Dan Carter (Canterbury), Jerry Collins (Wellington), Rico Gear (Nelson Bays), Carl Hayman (Otago), Doug Howlett (Auckland), Chris Jack (Canterbury), Campbell Johnstone (Canterbury), Byron Kelleher (Waikato), Sione Lauaki (Waikato), Richie McCaw (Canterbury), Leon MacDonald (Canterbury), Justin Marshall (Canterbury), Aaron Mauger (Canterbury), Keven Mealamu (Auckland), Mils Muliaina (Auckland), Ma'a Nonu (Wellington), Anton Oliver (Otago), James Ryan (Otago), Sitiveni Sivivatu (Waikato), Conrad Smith (Wellington), Greg Somerville (Canterbury), Rodney So'oialo (Wellington), Mose Tuiali'i (Canterbury), Tana Umaga (Wellington [capt]), Ali Williams (Auckland), Tony Woodcock (North Harbour).