This article is fake. The 'Pericope Adulterae' may not have been original to John's gospel, but has every indication of being authentic. It was described by Papias (a student of John) and other key early Christian witnesses.

https://www.academia.edu/50853545/The_Canonical_Status_of_the_Pericope_Adulterae_John_7_53_8_11_