Well - obviously - the end is sealed once the shrink wrap is done as suggested on the blog.
Can you get gusseted vacuum pack bags for chicken carcasses? I have never seen them.
I wouldn't be able to get a whole chicken carcass into a vacuum bag and have enough plastic left over at the ends to make a good seal. We only have a basic vacuum packer which is great for sliced stuff like bacon etc but the bulk of a chicken carcass would make it difficult to make the ends meet for a good seal on our machine.
That's why I like this method for more bulky items. Certainly for us - I doubt the chicken will be in the freezer for very long.