"but my understanding is that within 1st century Jewish culture there were no circumstances in which it was morally acceptable for younger siblings to dress down an older
sibling."

OT evidence goes along with that notion, doesn't it? I mean, David wasn't presumptious or lording it over his big brother. And then there's Joseph who got them mad with him when he popped off about that dream he had. The younger sibling who get authority over his elder seems to require divine intervention and even then it is resisted. Thanks for the evidence, Markus.
Glenn+