NHL rule (43.1). A goalkeeper is not “fair game” just because he is outside the goal crease area. The appropriate penalty should be assessed in every case where an opposing player makes unnecessary contact with a goalkeeper. However, incidental contact, at the discretion of the Referee, will be permitted when 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 contact.
Lucic got a penalty so that's good enough for me. The whole Buffalo team, however, should get suspended for not sticking up for their goalie. Bunch of pussies got scared of Lucic, Buffalo's true colours showed that night. Terrible teammates.