Here are my thoughts on this subject......
When pipes, hoses, etc. are under pressure and full of water, the water expands when it freezes and depending on the pipe / hose material, it can split based on how much the material is able to flex and expand.
Flushing the lines (cold and hot) with antifreeze will circulate it through all the lines if you open every faucet / shower until it is pink and then blowing them out with air will prevent any damage from freezing.
If you have emptied the fresh water tank, there is no need to put any anti-freeze in the tank. Even with a little residual water that might freeze, it won't do any damage because there is plenty of room for expansion.
If you have blown all of the water from the ice maker supply line and the ice making unit, you should be just fine.
That being said, the RV anti-freeze solutions out there also claim to lubricate seals, etc. Running it through the system and then draining / blowing it out would be good enough for me. Most of them have burst protection to -50 to - 100 so if the tech filled the hot water tank with it, there should not be an issue but I see no reason to do it.