There seems to be conflicting criteria:
To be considered, a player cannot have previously played more than 25 games in any single season, nor have played in six or more games in each of any two preceding seasons, in any major pro league. In addition, Calder winners must be 26 years old or younger on September 15 of their rookie season.
or
To be considered a rookie, a player must not have played in more than 25 NHL games in any preceding seasons, nor in six or more NHL games in each of any two preceding seasons. Any player at least 26 years of age (by September 15th of that season) is not considered a rookie.
so which is it for Kuzmenko?