It is not effective, if this is not the type of "attack" you have to defend against vs. plugging a Raspberry Pi with some nefarious software into the same network.
But yes, I think preventing random users from opening ports listening to the world is a good idea, I don't think it should be done this way. First of all, it possibly should affect all ports and there should be a configuration file which regulates which user can open which port. Tying that privilege to the root id is the worst possible way, as discussed. The right way is to define a mapping, which userid may open a port below 1024 or at all. That would also ban e.g. a malware to operate a backdoor server on a non-privileged port. And would mean that no service requires to have root rights.
These things you could do to improve, not weaken the initial concept.
