The team arrived back in Sydney Thursday afternoon after suffering a tenth series loss in 11 years and Gallen did not stop to talk to the waiting media.
With the series already lost, Mortimer said he wants to see a different side run out in the final match of the series.
"There's one game to go and never has there been an opportunity to bring some young players into the fold, just like Queensland did 12 years ago," he said.
"I guess that might be our Captain, other players as well because it's not going to make a difference now."
Game three in Sydney is set to be Gallen's farewell in the Blues jersey after declaring this year would be his last State of Origin series.
Coach Daley said at this stage he still plans to pick the captain to play in game three.
"Everyone is entitled to their own opinion and if he's (Gallen) fit he'll be there," Daley said.
Mortimer backs Gould's calls for overhaul
But Mortimer believes it is the perfect time to make a change.
"If I was a selector I'd be looking to the future," he said.
"It's no disrespect to Paul Gallen, I think the world of him as a bloke and a player but we haven't won it this year so next year, it's about planning for that, so why not make the third game a starting plan for 2017.
Gallen led New South Wales to a drought-breaking series victory in 2014 and Wednesday night was his 15th game in charge of the Blues.
Mortimer's comments come after the team's most successful coach Phil Gould accused senior players of being selfish.
"I have been astonished by the selfishness around this camp and around this team and in the leadership group and I don't think it has allowed the team to evolve," Gould said after the loss.
"I think Gus (Phil Gould) has a good point there, I think we have to be looking forward to getting young players that we know can do it and be successful," he added.
Despite calls for the Daley to make changes for next month's game, he says he won't be using the match as a chance to experiment with new talent,
"For us it's about picking the best team, there's no such thing as a dead rubber in origin," Daley said.
One change he might be forced to make is halfback Adam Reynolds who is set to miss the game with a shoulder injury.
Reynolds said he hopes it doesn't rule him out for too long.
"It feels pretty good at the moment. It's not feeling like a season-ending injury. I'll hopefully get some good news."