My personal thoughts:
Bunnies' GI systems are so sensitive, that I think anything outside the normal dietary foods would be too much of a risk to even chance.
In other words, a bun even ingesting a little bit of the much higher protein and fat content that cat food contains (no matter what type of cat food it is) would be taking a chance of causing your bun to have diarrhea problems, and as an extension could wind up taking a chance with your bun's life.
Thereby, I'm of the opinion and thought that it's just not worth keeping anywhere the bun might get to it. I keep anything and everything outside my buns' running space...including both the cats' food and water. That way, they can't even share it through drinking from the same space.
As you can see, I'm extremely cautious about what my buns are allowed to be around...and will do anything possibly in my power to keep their area safe, bunny-proofed, and without anything that would possibly pose any danger if ingested.
I even make sure to only give them toys that are either metal or wood...because if they ingest the wood, it's okay...and they cannot ingest the metal, so that's okay. I avoid even the hard plastics, because I've known my girls to be able to chew such things, and I don't want them to ingest them and have a problem with intestinal blockage.
I think with bunnies...prevention is the best, wisest thing to do.
Just my :twocents
Hugs and love to you and yours!
Rosie*