The above answer are correct for hiding a column from display on screen. However, you say that "t_header is pointing to some structure which is being used in some other programs as weel. This structure is enhanceed with the new field which is of type table." which means that your table is a based on a deep structure with a nested table as column. I can't even get the factor method to compile for a table fitting this description never mind getting a dump when the display method is called but whatever the reason for that difference if you table contains a column that is a table I think you will need to remove that column completely rather than just hide it from display.
The quickest way to do that would be to create a local structure type that is the same as the line type of t_header minus the offending column. Then create a local table using this type and copy the data from t_header to the local table and pass this local table to cl_salv_table=>factory.