Giants head coach Doug Christiansen is currently in Latvia with Team GB, but is unhappy with the ruling in relation to two incidents during his side's clash with the Cardiff Devils on Sunday past.
Stewart had been assessed a two-minute minor, but further disciplinary action was requested by the Devils and the committee reviewed the game.
They subsequently awarded Stewart a match penalty for checking to the head, which carries a three-game ban, and a further three game ban for kneeing an opponent.
The third three-game ban, which can be appealed against, was added because two serious match penalties occurred during the same game.
"These two incidents in the game were worthy of match penalties and, after a review by the committee, we have decided to impose the minimum tariff for each incident," the Elite League's head of discipline, Simon Kirkham, said.
"As both incidents are nasty and happened in the same game, we have decided to add an extra three matches to make a total of nine."
If Stewart has to serve the entire ban, he won't be available for selection until mid-March.
Meanwhile, Team GB fell to a 6-2 defeat in their opening Winter Olympics qualifier against hosts Latvia - despite the strong influence of Giants players.
Craig Peacock netted the second goal for the visitors, after a quality pass from Giants teammate Colin Shields. And it was former Giant Rob Dowd who had opened the scoring for Team GB.
But the result leaves them bottom of their group with two matches against France and Kazakhstan to play - Team GB must top the group in order to qualify for Sochi 2014.