I had to work through this backwards to understand it. None the less, I am concerned that only one product formed. With the proposed mechanism, the cyclopropane cold open two ways to give similar products. This is what I think happens. It does no decarboxylation initially, but now the most acidic proton is that alpha to the benzo group. Open the cyclopropane to give the enolate of a beta keto-acid. You can rationalize a path for the remainder of the steps.