He is, but as he said, the CSV format doesn't support that kind of styling. Only Excel's native binary .xls format will support that. If you save a worksheet to csv in Excel you normally get a dialog box warning you of this.
You could try a PHP class that writes in the xls format. I don't have any links, but I know that one exists. The new XML version of the Excel format is also a possibility, but that isn't compatible with older versions of office.