Hong Kong protest: City reels from 'one of its most violent days
Activision Blizzard's share price had fallen by 2.3% by the close of trading on Tuesday.
However, the backlash was unlikely to cause serious commercial problems for Activision Blizzard, said James Batchelor, UK Editor at GamesIndustry.biz.
"It's negative PR and that's never great for a company but I can't remember an instance where a consumer-led boycott has led to a significant drop in sales in the video games industry," he told the BBC.
"These games have such a vast audience that I would almost say almost half don't even know what's happening... The vast majority of Call of Duty players are so casual, so mainstream."
Seth Barton, editor of gaming industry magazine MCV, agreed that the boycott was unlikely to have a significant impact.
Activision Blizzard didn't have much choice in the matter, he argued: "by allowing any such protests it would have to either allow all such protests, or become arbiter of what's acceptable and what's not".
BBC News has contacted Activision Blizzard for comment.
Ng Wai Chung is the name of the gamer banned for 12 months by Blizzard. He uses the pseudonym Blitzchung.
During a post-match interview on the official Hearthstone Taiwan video stream, he donned a gas mask and shouted: "Liberate Hong Kong, revolution of our age."
Blizzard said tournament rules said players must not offend people or damage the company's image.
Other US technology have become embroiled in the controversy over Hong Kong.
China's state media this week criticised Apple for listing an app in its app store designed to track the movements of police officers in Hong Kong.
The People's Daily newspaper said the app was an endorsement for "rioters".
The tool, HKmap.live, was not named explicitly by the newspaper.
It works by asking users to cite the locations of police and anti-government protesters. This data is then displayed on a map.