Weise was hammered by an illegal check to the head from the New York Rangers' John Moore in Game 5, costing the Rangers defenseman a two-game suspension. Weise went to the locker room but came back to finish Game 5.
Therrien insists concussion protocol was followed and the NHL on Thursday also told ESPN.com that the protocol was properly followed.
The league reminds clubs on a constant basis about the importance of following the protocol, stressing to teams that it's one of the league's highest priorities.
Defenseman Alexei Emelin, meanwhile, who missed Game 5 with an undisclosed injury, also was out for Game 6.
In other injury news, star goalie Carey Price once again took to the ice near the end of the Canadiens' morning skate. He took shots from his teammates for the first time and worked mostly with goalie coach Stephane Waite for about 30 minutes.
Therrien has said repeatedly Price will not play in this series.