Apparently all food value has been removed to avoid vermin being attracted to it so it's doubtful it will add much as a fertilizer but your garden would be a handy place to dispose of it harmlessly.
Keep in mind, I read an article about this stuff and those temps you WANT in your compost are what they need to compost properly. I've seed 'biodegradable' bags take years to biodegrade because the temps needed are not really achievable in reality of where the garbage actually ends up! You're soil temps being used in the garden won't be enough for these to actually breakdown in an proper amount of time.
But I don't think it will hurt your garden either! :/
Well, if you run them under water they disintegrate so they do break down. I doubt I'll put them in the garden though since they don't really contribute anything.
i always found that stuff really neat when i worked at our local equine clinic when it came in some packages! though taking and wasting the water just to get them down the sink was just a little ridiculous. i like the idea of throwing them in the compost much better! the rain will make them break down better than having to pay for the city water. though i don't see much use for them as a fertilizer.