That's kinda the point. We need rules because Nazis (and Tuskegee, etc.) but it's not clear we need these rules about pen vs pencil.

The pen vs pencil thing is a total canard by the author, who is looking to 'dress-up' his indignation. Hand the form to the subject. Hand a pen to the subject. Subject reads and signs the form. Take the form from the subject. Take the pen from the subject. Job done.

It's not like the patient will go bonkers stabbing-crazy the millisecond their flesh touches a pen.

The first part is real, and the second part is the joke.