Not for semantic reasons..
But at the moment on a std. join you only generate reorderable if user explicitly defines UNORDERED don't you?
Which (at the moment) is what will trigger the parallel helpers..

In this case we know smart=unordered, but I'm not sure we should therefore automatically start using the parallel helper..
If you already generate JFreorderbale on a standard join, when _you_ deduce order not needed.. then no reason not to here too.