You would feel better using antifreeze. And be safer.
Truth is. IF you are going to run antifreeze thru it. Blowing it out first is a waste of time. The antifreeze will displace any water in the system. that is what it does.
Now next thing. IF you use the winterizing kit inside the RV. Please remember to let the antifreeze run out the city water connector. There is a button inside the hose connector that you can press with a screw driver. However, Remember to stand to one side, as there will be pressure on it. Ask me how I know.