Mark, I've already said this once but I'll try again. The argument that you can cut through the floor to install a cage bar is only tenable IF the bar is necessary to or enhances the function of the cage. By your logic I could cut a hole through the roof, stick a tube attached to the cage through it, and mount my videocam on it.

:-) Same, exact logic.

I do think the pictured solution is legal or at least arguable in good faith.