If they used Nirvana, I'd want it to be subtle. Prince's music in the museum scene took me out of the movie.
I'd probably choose a more somber Nirvana song to go with a Batman movie. Probably something from MTV Unplugged, i've listened to Nirvana's MTV Unplugged while reading Batman comics more times than i can count, it's a good combination. And rock music shouldn't take away from a scene that should probably be using an original score.
But think about the way that they used Chris Cornell's song "Seasons" in MOS. They could do something like that for Nirvana. Zack Snyder clearly isn't averse to grunge bands if he used a Chris Cornell song. It's funny, you can hear Cornell in Avengers and MOS, in MOS, it's his solo act, in Avengers, it's with Soundgarden.
I first heard the song "Seasons" on the Singles soundtrack, which also featured some other amazing grunge bands like Mother Love Bone, Alice In Chains, and Smashing Pumpkins. It was pretty awesome to hear that song come on in MOS. My friends and i have similar taste, we all love 90s rock and we all looked at each other approvingly when that song came on in the theater.
I'm not saying that this song should be in a Batman movie, just posting because it's awesome

Nirvana with the Meat Puppets, playing Oh Me
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