It can, just set the Operator to None:
            desc.Operator = FilterOperator.None;

The proper way to change the default filter operator for a column is to add a FilterDecriptor for it with the Operator set and to also set its IsFilterEditor property.

            FilterDescriptor desc = new FilterDescriptor();
            desc.PropertyName = "col1";
            desc.IsFilterEditor = true;
            desc.Operator = FilterOperator.EndsWith;
            radGridView1.Columns[0].FilterDescriptor = desc;

More information is available here: http://docs.telerik.com/devtools/winforms/gridview/filtering/setting-filters-programmatically-(simple-descriptors)#using-simple-filterdescriptor