"But the claim I am trying to refute is that this works with ANY application doing ANYTHING."
"And yet it moves." -- Galileo, responding to the people of the day who argued that the earth was the centre of the universe.
The fact is that WiFi assist works. So clearly the problem is in your inability to work out how to do it. That you don't know everything as you think you do. It's not that it doesn't work.
So what BasilBrush, and the press releases from Apple imply, is that OS9 has a new feature no other OS has: it can transparently make streams continue, on another interface, with no support from the application software.
I've since been informed that Samsung have implemented the same thing on some of their phones this last few months.
Your idea of what's not possible is wrong. You have a flawed model.