Efectivamente, Tarantino no competía en los premios del gremio. Los nominados eran estos:

Original Screenplay
“1917,” written by Sam Mendes and Krysty Wilson-Cairns
“Booksmart,” written by Emily Halpern, Sarah Haskins, Susanna Fogel, and Katie Silberman
“Knives Out,” written by Rian Johnson
“Marriage Story,” written by Noah Baumbach
“Parasite,” screenplay by Bong Joon Ho and Han Jin Won, story by Bong Joon Ho (winner)

Adapted Screenplay
“A Beautiful Day in the Neighborhood,” written by Micah Fitzerman-Blue and Noah Harpster, inspired by the article “Can You Say…Hero?” by Tom Junod
“The Irishman,” screenplay by Steven Zaillian, based on the book “I Heard You Paint Houses” by Charles Brandt
“Jojo Rabbit,” screenplay by Taika Waititi, based on the book “Caging Skies” by Christine Leunens (winner)
“Joker,” written by Todd Phillips and Scott Silver, based on characters from DC Comics
“Little Women,” screenplay by Greta Gerwig, based on the novel by Louisa May Alcott

Por cierto ( y esto es opinión completamente subjetiva), lo de Waititi ganando en guión adaptado me parece una broma de mal gusto...