Legitimacy based on what? Recongition by the UN? Lots of governments even predating the UN have been long accused of rights abuses. How many people affected, and proven so by what basis constitutes infractions beyond moral right to be trusted by NSO. I'm asking people to really grapple with this.
My point being that there’s precedent for restrictions - we don’t sell nukes to anyone, and the companies which make advanced weapons systems have to get things like ITAR approvals. What would be especially powerful would be revocation: if a country is found abusing their access to this tool, they are blocked from purchases of any sort for a decade. Unfortunately, given Israel’s current politics it’s extremely unlikely that anything would happen since there’s no way to write a policy which would continue to allow their own usage.