he put the detailed case for the high airfares into/out of Canberra --- showing in detail the airport charges and their proportion of typical fares, and why no Jetstar in Canberra --- airport charges make it un-viable
The airport charges apply per pax, independent of the airline. A $300 QF airfare has $25 in airports fees attached and a $125 JQ airfare would have the same $25 attached. How many pax will buy the $125 JQ rather than the $300 QF? That's what Joyce is protecting by not putting JQ into CBR.
Additionally, the front end of those QF aircraft are most likely all filled very lucratively and exclusively by the taxpayer. The $300 seats down the back are just the gravy. Why give those away?