I've been cooking SV many years and have never used the method to thaw an item solely for the purpose of "thawing" it. On the other hand, however, I've used SV to cook numerous items from the fully frozen state to finish, or semi-finish, countless times. Sometimes, I've done it purposefully, and other times I've done it as a back-up method when I haven't allowed enough time for an item to defrost in a more traditional manner. When I do it to a semi-finished state, the item is then finished in the smoker, oven, or grill.
With beef, pork, and lamb, I've done it with steaks, chops, loins, ribs, roasts, etc. Most recently, I did it with a 3 lb. cleaned and frozen "lump" of beef cheeks that I used for ravioli. I've also done it with frozen poultry parts, and thick cuts of frozen seafood such as halibut and swordfish.
It's worked very well every time, and I've never had a problem. Also,I've never been concerned about food safety.