Ann: Trading Halt, page-62

I don't disupte that the government and regulatory bodies are at the behest of Qantas but they certianly didn't put a gun to Rexs head to launch 737 ops.

Rex thought they fill the void left by Virgin when they went under (as VA did post Ansett), only they didn't count on Virgin being saved by Bain.
They didn't have the resources to competed with VA and QF, and combined with thier own infighting while throwing good money after bad they got exactly where they they have found themselves.

Bonza was a whole different story as they operated in a space the incumbents didn't think made sense and had never shown any interest in.
Apparently Bonza itself was sustainable-ish, but the parent company ultimately dragged it down. I don't think QF or VA were anywhere to be seen in that saga.