So you're arguing that we shouldn't call the operation in question || because it's pretty much the same, mutatis mutandis, as the hstore operation of the same name. You've lost me.
Hopefully this helps. Peter's argument, as I understand it is:
In hstore @> means unnested containment, in jsonb it means nested containment. Therefore, when an hstore operator is applied to jsonb it gets "nestedness" as jsonb is nested and adds that nestedness is an important thing that sets it apart from hstore. Therefore, since || is unnested concatenation in hstore, it should become nested concatenation for jsonb.
I don't know if the argument is strong enough but it does make some sense.
