You are exactly correct TCH but unlike a DOS boot disk, you can make your own "1050-2-PC" cable as per the directions. Perhaps if you are not confident enough in your electrical skills to do it yourself, could you find someone to do it for you?
You would need to get another SIO cable to cut up to make your "1050-2-PC" cable so some source of Atari parts needs to be found on your side of the pond.
has sio2pc cables for sale, just email him. And then you could use your 1050 on your Atari system to write the DOS disk after booting up your Atari via the sio2pc cable from your pc which has the DOS disk mounted while running the sio2pc program. So this is yet another way to get done what you need done. The 1050-2-pc cable is the simplest way but not the only way. The sio2pc cable will prove to be the better choice of cables to have and use as it will provide much more benefits. The downside is that there is a slightly steeper learning curve with it.