That method is unreliable for a document to be used by others, because the display/hiding of text -and its printing - is controlled by their Word configuration, not the setting of the font attributes. The method there is extremely easy to circumvent, without changing any of the document content as the method presumes to be required. To display hidden text, simply go to File|Options|Display and check the 'hidden text' option. A similar option on the same dialogue box allows it to be printed also.
For more robust methods, see:
https://www.msofficeforums.com/word/...orm-field.html
https://www.msofficeforums.com/word/...-question.html