The post has been shared across social media where it is infuriating league fans.
A Facebook user who watched the game at HeadQuarters said it was a case of "some clown" ruining it for the majority.
"We had a really great night there last night watching Origin, the TV screen is amazing for sport and the crowd seemed really great during the game. Obviously some clown has ruined it for the majority," Tim Gregory said.
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The expensive screen was reportedly spared but the bar added in a comment that "they decided (ironically ) to smash up pictures of Conor McGregor and Willie Apiata ... tough bastards being smashed up by low-life league loving losers".
"We've had a year of great rugby, the Lions tour for example, plus cricket and racing etc ... and no problems, then the league scum drift in and try to wreck the place," another comment said.
"I've made my decision, never again you losers, you behave like animals and I'll treat you exactly like that, with pleasure. Apologies to those who love that game and behave, but I'm not having my precious asset put at risk again," the bar added.
Several social media users blasted the bar for the "unprofessional" post and for stereotyping league users.
"Wow what an unprofessional post! Blame it on the individuals but don't stereotype all league supporters, trust me there is plenty of idiots that support rugby as well," Cath Howard commented.
It is not clear what the extent of the damage was.
HeadQuarters Viaduct has declined to comment.