Possibility of turning off Copy Option for Pdf Text Form Field.

I am doing this, But what I want is to secure a PDF with a Document Open Password such that the end user of the PDF should only be able to view it. I am able to successfully disable Copy for most of the PDF content, but strangely enough the Form Field Value can still be copied.

I came across some information at How do I disable copy/paste for most (but not all) of a .pdf?

To quote one of the replies, "I am pretty sure you can turn off copy and paste options in security, but form fields will still be available for completion (with copy and paste).I believe the options apply to the basic document, not to markup (form fields)."

I just want to be sure this information.