With James Gunn's firing Disney proved that they have no qualms about firing anyone that could negatively affect their family-brand image, no matter how successful or productive they've been for the company.
That's what influenced Rian Johnson to delete over 20K tweets shortly after Gunn's firing was announced.
However, Johnson refuted any notions that the decision was influenced by anyone at Disney, stating that he simply wanted to cut off any potential controversy before it had the chance to rear its head. He's not even sure if anything in those older Tweets would have landed him in hot water.
Though controversial, Star Wars: The Last Jedi grossed $1.33 billion USD at the worldwide box office from an estimated production budget of $250 million. Lucasfilm subsequently hired Rian Johnson to spearhead development on a new trilogy of Star Wars films, wholly separate from previous Episodes.