I read this and it does not say he shot down rumors of a justice league live action film despite that being stated in the title. This is all it has to say regarding Justice League:

DC announced over the weekend a Justice League animated film that would be released in 2024 and it’s based on Crisis on Infinite Earths. Many deduced that this could be the basis of a possible live-action film by Gunn. However, Gunn shot down the rumor by replying to a fan with a simple “No,” on Threads.

It simply states there is no Justice League film based on Crisis on Infinite Earths coming. This article mentions 3 heroes—Guy Gardner, Hawkgirl and Mister Terrific—but fails to mention they also added Anthony Carrigan as Metamorpho to the cast as well.

Honestly though, whether the movie is labeled as such or not, once you reach a certain number of DC heroes teaming up it becomes a Justice League film by default.