Fundamentally, Firefox is forcing the addon vendor to overwrite the users.js file without the users permission. What's more, these users only got this overwrite by explicitly allowing it.

So on one hand the reviewer is saying modifying the users.js setting without explicitly saying what it does, even though it required a separate process, was a bad thing to do. And their way of rectifying that is to do the same thing, only this time without any user interaction.