I feel it's OK if you have a 'default' sort setting which is applied in the absence of sort settings being provided to the procedure.
That will make the code re-usable and flexible going forwards....what if, for example, you wanted to allow users to define the sort settings themselves?
I don't think it's a violation, considering many tables have obvious default sorting logic that would otherwise need to be re-applied time and time again. And you are correct in saying it's more effective to apply sorting at the database level.