I would think the state can do whatever it deems necessary for the protection of health and life. In other words, whether it's necessary or not is not for an external party to determine. There may be an external challenge that a particular provision de-facto serves as a non-tariff barrier to trade; the onus of proving it is not necessary for the protection of health would lie with the challenging party. In reality, it is extremely difficult to mount such a challenge. That is why GMO is off limits in the EU, while Canada and the US happily grow genetically modified crops (but can't sell them in the EU).

In my view the challenge is not in the words "have rights" but in "to take measures". In other words a right is never standing alone, it is the right to something. And of course, if the measures taken go beyond the aim specifically designated, here "to take measures necessary for the protection of health and life", the state could be found to surpass its rights.

Theoretically speaking, I cannot see an obligation to consummate rights stipulated by a treaty.

A right is a provision envisaged to your benefit but you can abstain from that benefit. You have the right to walk across the street with green light but unless you obviate others to do so, no-one will harass you when you decide to wait for another five minutes, right? So not benefiting from rights granted may look weird but not as a violation of a treaty.

Of course, as regards your treaty subject, I can imagine that a different logic may apply.

This specific provision is not stating an obligation, because it is provided as a protection from potential harms (if something endangering its citizens occurs, the State can take measures to protect their health and life), but the protection of health and life is an obligation resulting from other provisions both internationally and nationally.