I'm surprised your flight wasn't on VA metal to start with. Obviously the price was cheaper for your work and with the connection type you wanted it listed that option. Are you sure it wasn't booked on Delta website? If booked on VA you could have used their counters in SYD.
I too have found Delta useless when it comes to what is/isn't benefits for anyone with VA status. But surprised about the VA staff at LAX as I've found them to be excellent with helping in the past.