Muscles can help you by contracting, or they can help you by being compressed. Basically reverse band rows teach you to make your lats hard on the way down which cushions the load at the bottom by compression of the lats. Hard flexed lats will actually put the humerus stable pointing straight down to the feet or even slightly forward of the feet, and in either case, maximally flexed lats will occur with a bar OFF the chest.
But what you are proposing above is a concentric contraction of the upper back to pull the bar down. When lowering a bench, the prime movers are still doing the work to lower the bar eccentrically. The upper back ( traps) is most important to guiding the bar because those muscles actually attach to the scapula, while the lats contribute as secondary stabilizers. What you are saying is nice in theory, but that cushion you're talking about isn't going to do anything to move the weight and is very low on the importance scale.