Do what from orbit? It's a first stage it will never make it to orbit.
It also is looking to come to zero velocity, good old friction can do most of the work. Depending on the flight profile chosen it may only be necessary to fire the engines for a few seconds to go from terminal velocity to zero.
Since the company doing this is now supplying the space station they might know a bit more about rockets than you.
“Do what from orbit? It’s a first stage it will never make it to orbit.”
Well, now, let’s see. They wanted to land a vehicle upright so that I suppose that it would be from orbit, no? When are vehicles expected to land upright if not from orbit?
If you are saying that first stages would be landed upright then I still say that too much fuel is required.
Why do you assume that ‘they’ may know more about rocket science than I? You do know what ‘assume’ does, don’t you? ;-)