Yes, in that passage alone Christ suggests that his disciples are His brother, or sister, or mother, depending we assume, on sex and age. But the expansive use of "brother" to refer to spiritual kinship we find in many places.
My point is that the passage does not say anything about Christ's disagreeing with His mother or other kinsfolk. It is not them, but rather some unspecified listeners who think He had gone mad.
Just like with "brothers" being necessarily Mary's biological children, we can interpret this as a sign of a disagreement, but the text does not compel us to do so; it is a matter of interpreting the text.
"Yes, in that passage alone Christ suggests that his disciples are His brother, or sister, or mother, depending we assume, on sex and age."
No. He suggests all are His bros, sisters, maothers ect. That was in response to the announcement, "your mother and brothers are outside looking for you".
"But the expansive use of "brother" to refer to spiritual kinship we find in many places."
Sure, but not in this passage, or John 7. In this passage, the distinction is made between his bros, as in related and close to Mary and all others.
" My point is that the passage does not say anything about Christ's disagreeing with His mother or other kinsfolk.
I didn't say He did. I have no idea where you got this from.
Re: why he didn't refer to John the Baptist as "brother John"?
"1. The recorded speech of one of them to the other tends to be coached in lofty terms: "I must decrease for He must increase"; "so it becometh us to fulfill all justice". This precluded "brother" as an affectionate term."
Irrelevant. THe term bro has no connotations of stature.
"2. The expansive use of "brother" is common when several relatives are addressed collectively. When just one person is addressed, a more precise term, such as "cousin" would be typically used."
No. The term may apply to cousin. It is not a term that refers to generic relatives.
" 3. John was renowned in his own right, while James a.o. were only known in relation to Jesus."
Both John and James were only "renowned", because of the existance of Jesus.