He might have coordinated the evacuation though, nobody saw the destruction of an entire star coming.
Prehaps he decided to buy some more time and get some transports free for civilians, just like the captain that goes down with the ship if there are not enough lifeboats.
I think he wanted to make sure that all civilans will be evacuated, then when supernova started he knew that he won't make it out.
If it was like that, the tone of the last transmission would fit the theory of heroic sacrifice.
Also I don't think he was from the central, but rather from a local in-system command (Capella was fairly important, so a command post located there would have some generals and admirals on board. It just happened to be close to GD, so nebula ops were most likely controlled from there.).