According to Deadline, the decision to rehire Gunn "was mulled and actually made months ago, following conversations with Disney studio leadership and the team at Marvel Studios." The site says the decision to reverse Gunn's removal came after Walt Disney Studios chairman Alan Horn met with Gunn "on multiple occasions to discuss the situation. Persuaded by Gunn’s public apology and his handling of the situation after, Horn decided to reverse course and reinstate Gunn."
Production of Guardians of the Galaxy Vol. 3 was supposed to begin last fall 2018, but was put on hold following Gunn's firing, and since then, a replacement director was never found. Deadline also points out that Marvel "never met with or considered any other director" for the movie, despite rumors that directors Taika Waititi and Adam McKay were being considered to direct. Additionally, president of Marvel Studios and producer Kevin Feige said that Gunn's script was still going to be used for the film.
The site also revealed that Gunn will direct the project after he concludes his work on Warner Bros.'s Suicide Squad 2, which he is slated to write and direct. Guardians of the Galaxy Vol. 3 is scheduled to debut sometime in 2020, however, it's still unclear if that will be the case since Suicide Squad 2 is set to premiere in 2021.
For the full story, head on over to Deadline.