Clearly, your concern is clostridium botulinum. Freezing does not kill the spores, which potentially produce the toxin that causes botulism. However, it does stop their growth, as long as you freeze quickly, and your freezer remains below 0 degree F (-18 C). Therefore, freezing is safe for the storage of garlic.
You will need to take care when thawing. It is best to use the refrigerator if you plan thaw the whole package.
Now, while the vacuum bag is not a safety issue in this circumstance, there are probably more convenient ways to freeze your garlic so that you don't have to put a bunch of garlic through freeze thaw cycles, which not only will destroy the texture of the garlic, but will also create a higher risk of spoilage. These include, (a) just place whole cloves in smaller zip freezer bags, and freeze flat so that you can remove a clove or two at a time and keep the rest frozen, (b) chop and freeze flat in zip bag, then grate or chop off what you need, or (c) blend with 2 parts oil and freeze in a container (do not keep this at room temperature). This should remain soft and allow you to scoop out what you need to use.