Yes, it was a sick kind of irony. To understand it, though, you have to have some knowledge of the punk scene in 1977. There were neo-Nazis who infiltrated the punk scene to recruit the disaffected youth who flocked there. It was a mockery of these people, and of their particularly crass attitude toward the weak, similar to the song “Kill the Poor” by the Dead Kennedys.
But you’re right, who can blame Bell Canada for apologizing? A respectable company can’t afford to offend anyone, no matter if the offense is misconstrued or not.
I dont think the sex pistols made light of genocide in the song - it was a comment on the Holocaust and hippies.