You cannot protect a column, but you can go to Preferences ==> Tweaks and set the "doubleclick_on_library_view" tweak.
Code:
#: Control behavior of the book list
# ID: doubleclick_on_library_view
# You can control the behavior of doubleclicks on the books list.
# Choices: open_viewer, do_nothing,
# edit_cell, edit_metadata. Selecting anything other than open_viewer has the
# side effect of disabling editing a field using a single click.
# Default: open_viewer.
# Example: doubleclick_on_library_view = 'do_nothing'
# You can also control whether the book list scrolls horizontal per column or
# per pixel. Default is per column.
This will allow you to avoid accidental editing.