The extra weight to keep the cabin from disintegrating under force alone would make this totally impractical. What happens to the rest of the plane when the cabin is released?. The entire frame and wings would buckle and very likely end up tangled in with the parachutes. Likewise, the weight to keep the separate air-frame/cabin and wings strong would wind up being totally impractical. Plane structures work because the ENTIRE air frame supports the massive amounts of force that are applied to a plane during flight. The balancing act between weight and strength has been very carefully crafted over the years and this proposal pretends like that doesn't exist.
This is clearly manager thinking. It waves it's hand at very complex technical details that are inconvenient.