Hello Maarten,

In the iggrid Updating features to enable only one column editable, you have to set other columns readonly.It would not change the UI of the other column.

Your code would be like this:
$("#grid").igGrid({
    features: [
        {
            name: "Updating",
            columnSettings: [
                {
                    columnKey : "Name",
                    readOnly: true
                }
            ]
        }
    ]
});

I have created a sample application please find the attachment and let me know if you need further assistance.