It is not necessarily that the priest went off the reservation. When we were covering the passages in which Jesus’s brothers and sisters, we did not skip over it. We simply read the passages as they are written. Maybe the priest personally believed that the brothers and sisters were actually Jesus’s cousins or Joseph’s children from a prior marriage. He didn’t say. He didn’t offer an opinion. He didn’t try to twist the meaning of words. He offered no spin. He just presented it as it is written without offering opinions, theories, dogmas, or doctrines. We were in the “no spin zone” to borrow a phrase.
It does seem that if Jesus had any brothers Jesus would not have asked John to take care of his mother.