No. It proves Jesus was addressing the disciple whom he loved and was placing Mary in his care.
If your assertion is correct then Paul is a liar in Galatians 1:19 where he identifies James as the brother of the Lord.
That would make Matthew, Mark and Luke liars also as they identify Jesus having brothers and sisters.
Context is the key to understanding the verses regarding His siblings.
But my assertion is that the reader is supposed to identify with “THE disciple whom Jesus loved.†I am not claiming that Jesus was speaking to more than one person, only that we are to identify with the ONE to whom Jesus is speaking. Therefore, one would expect that the singular is used.
I agree He was speaking to one disciple.
Oh, and since John the Evangelist survived to around 90 AD, the notion that he was young enough to have a mother still alive around 30 AD is not mere speculation on my part. Sticking to strictly biblical sources, John survived at least until the persecution of Nero (late 60s AD).
It still remains speculation on either position regarding John's mom as we don't know.
I wonder why Jesus did not place Mary in the care of her other sons? My guess, and it is only a guess, is that the half brothers of Jesus, the other sons of Mary, were not born again believers yet. Later some, maybe all, did become BELIEVERS in Jesus, two of whom, James and Jude, wrote books in the New Testament.
:-)
“The son of you” implies that there are no other son.