iPhone 6s isn't even the oldest iPhone still receiving security updates, according to the page you linked. Ctrl+F for "iPhone 5s", and you will see that it rec

iPhone 6s isn't even the oldest iPhone still receiving security updates, according to the page you linked. Ctrl+F for "iPhone 5s", and you will see that it received a security update less than 2 months ago. And that's a phone released in September of 2013, making it almost a 10 year old phone by now.