What must be done to allow a user to edit a column that is not editable?

To enable a user to edit a column that is not originally editable, utilizing Field Sets on Project Task is the correct approach. Field Sets allow you to create a dynamic collection of fields that may not be editable in certain contexts but can be made so in others. By defining which fields are included in the Field Set, and configuring the settings accordingly, you can grant the necessary permissions or make changes to how users can interact with those fields.

This is particularly useful in scenarios where the default behavior of specific fields restricts editing, thus allowing administrators to customize how users interact with the data. Field Sets provide the flexibility needed to tailor the user experience without necessarily altering the foundational settings of the column itself.