That’s an easy question.
If the words “Son, behold your mother” were of no relevance to us, the readers of the gospel, they wouldn’t be in the gospel.
Your statement presumes that the only value you can derive from the Savior’s words must apply to you equally as to John.
With that premise, I can’t wait to see what you do with these inspired words in Matthew...
“So Judas threw the money into the temple and left. Then he went away and hanged himself.”