Well, then if it has worked safely for you, that is great!
I was a bit concerned with the fact that folks are using the butter flavouring and the information that came up recently about it containing a form of milk. Also, some folks use milk or cream instead of water in their all shortening recipe.
Actually, on the freezing and unfreezing and refreezing of cooked meat, I don't know about that. It was always not recommended before and unless some new information has come up, I wouldn't do it. I know that I have read that if you defrost in the refridgerator and then refreeze prevously frozen cooked meat, it is ok but this would be with the meat always being at a constant cool temperature. I would think that reheating it then cooling etc. would cause some risk of bacteria forming. So I wouldn't do it.
I would think that icing made with water and shortening would be far safer than that made with butter, crem or milk, in terms of the freezing thawing and re-freezing states. We also have to be careful about the term re-freezing which is usually meant in relationship to meat that is taken home from the store in a frozen state and then put into the freezer.
The safety of refreezing a lot of items seems to depend on them being kept at cold temperatures and in most cases once items are brought to room temperatures there is some issue with that.
I cannot find my source on the Internet, but here are a few sites with some information on safety with frozen foods.
Hugs Squirrelly Cakes