John Lydon was NOT cruel to animals
As many here agree, the portrayal of John Lydon (aka "Johnny Rotten") in this film was a completely fictional hatchet job. Beyond turning him into a one-dimensional bastard to accentuate Sid's innocence by contrast, they had the character encourage Sid to spray-paint a small dog after they broke into a car and found the pup inside.
"Go on, Sidney! Spray the beast!" he says.
In reality, John Lydon was not only a non-violent person, but very sensitive toward animals and even insects! He made a nature film about the life of bugs for children that showed feelings toward even the smallest of creatures. And he never called Sid Vicious "Sidney." He called him by his real first name "John" because he had known him by that name for years before the Sex Pistols existed. Alex Cox is a wanker with no respect for truth.