Actually no even if Version didn't allow it Samsung can do what they want with their products. You can go to any other carrier around the world and the result would be the same.
From personal experience, operating system updates are not given as options even though they are posted as such. Your phone will continue to harass you over the next several days weeks and even months to install the updates on your system. If you continue to refuse and or opt out the phone will find clever little ways to cause you to accidentally click OK to installing the update as it will become increasingly difficult to ignore the requests.