The author does mention the etymology of 'person' in an earlier article, so they appear to be aware of it.

"'Person,' by the way, has a neat etymology. It comes from the Latin persona, referring to a mask worn on stage. Per (through) + sona (sound) — the thing through which the sound (voice) traveled."

http://www.meltingasphalt.com/ux-and-the-civilizing-process/