Actually that is totally wrong. The rules actually dispel 'fair game' - Rule 69:
69.4 Contact Outside the Goal Crease - If an attacking player initiates
any contact with a goalkeeper, other than incidental contact, while the
goalkeeper is outside his goal crease, and a goal is scored, the goal
will be disallowed.
A goalkeeper is not “fair game†just because he is outside the goal
crease. The appropriate penalty should be assessed in every case
where an attacking player makes unnecessary contact with the
goalkeeper. However, incidental contact will be permitted when the the
goalkeeper is in the act of playing the puck outside his goal crease
provided the attacking player has made a reasonable effort to avoid
such unnecessary contact.
When a goalkeeper has played the puck outside of his crease and
is then prevented from returning to his crease area due to the
deliberate actions of an attacking player, such player may be
penalized for goalkeeper interference. Similarly, the goalkeeper may
be penalized, if by his actions outside of his crease he deliberately
interferes with an attacking player who is attempting to play the puck
An attacking player who, in the judgment
of the Referee, initiates contact with the goalkeeper, whether inside or
outside the crease, in a fashion that would otherwise warrant a
penalty, will be assessed an appropriate penalty (minor or major
and/or game misconduct) and will be subject to additional sanctions
as appropriate pursuant to Rule 28 – Supplementary Discipline.
http://www.nhl.com/nhl/en/v3/ext/rules/2014-2015-rulebook.pdf