Reddit mentions of Joss Whedon: The Biography

> However, in June, MGM announced that due to the studio’s financial difficulties, it was shelving Cabin indefinitely.

From his biography. After the bankruptcy, it did end up in limbo till it was bought by lions gate.

> At least MGM’s issues came after shooting was done and the film was in good shape. Goddard and Joss were frustrated, but they found a little consolation in the idea that if Cabin never saw the light of day through proper channels, they could always leak it.

So it was in a good enough shape that he felt it was still good enough to release, as in pretty much finished.

> But they discovered that Lionsgate truly cared about Cabin, which in turn helped them believe in it again, and reignited the vision and enthusiasm they’d been drained of.

So yes, it was lions gate who got the movie to the public. I don't see how I'm 1000% wrong.

All quotes are from his biography, where there were extensive interviews from joss himself and most of the people he's worked with.

ETA: Read the biography if you want more info.