To make it possible for a user to create their own custom Views in the Calendar, you have to set their Calendar module as MANAGE rights for the user.
But when you do that, it also gives any user the ability to edit , add or delete any of your "Category" settings too! That seems completely wrong. I would think an Admin should be the only one able to create and edit Category names and colours, otherwise we are going to end up with chaos over the colours and titles (we already are running into this problem a mere 3 weeks into using GO).
Just like a View, Category editing should be tied to assigning it to a Group or User access levels so that you could setup Admin and as needed, extra users, or groups of users, with the right to add, edit or delete categories.