Virgin Blue would require disabled passengers in some circumstances where they did not have a carer travelling with them to arrange for their own "assistance person" at departure and arrival points to help them on and off the aircraft.
I heard the DJ spokeswoman make that statement this morning and it clearly has absolutely everything to do with cost-cutting. That is an aspect of disabled access which almost every major airline in the world employs staff to assist in. But which off course, DJ wouldn't need to under the new policy!
QF will arrange a hi-lift to unload a wheelchair pax if that is necessary (as will most airlines), and will always have staff there to meet pax with wheelchair requirements if it is requested (as will most airlines). Have organised to have these things done many times.
Yes, it looks like and smells and quacks like DJ cost-cutting. Sorry guys.
EDIT: I'm not sure that the 'safety' factor is a particularly strong argument. There are numerous precedents in all modes of public and/or mass transportation for accommodating disabled passengers who may or may not be able to evacuate themselves in an emergency and would have to avail themselves of assistance from other passengers. That tends to be an accepted risk.