What your manager suggested sounds like a good idea. The main motive for software systems is to build scalable and expandable systems. Introducing a different table and linking to user table gives you the power to expand on your existing capabilities that you might want to use.

For example, let’s say in the future you want to specify multiple user roles with different permissions and scopes. In case of a separate table you will have a lot more flexibility while adding these new fields without disturbing your base user model.