You are just making this up. You were asked the other day where the Good Friday agreement or any Eu document said this was so, and you didn’t produce it. Just repeating this nonsense is not a valid argument.........
You need to read a bit more widely about Northern Ireland and the Good Friday agreement and the Northern Ireland Act 1998. May herself has said, that those with an Irish passport have Irish citizenship and therefore will have EU citizenship rights. So if a law is passed in the European parliament, say working directive with 2 years off with full pay for maternity leave, and will be enacted in the Republic, it will be relevant to those in the north with Irish citizenship. A person with an Irish passport - EU citizenship, will then be able to claim that benefit. If a company refuses it would go to the ECJ to rule on that issue.