Or, there is the third option .
(Im sorry if there was a third, I just kinda skimmed through your text.)
Osiris said that this was a world without light, but also without darkness.
The light and darkness have a final showoff, making the two sides of the dao balancing.(ying and yang)
<The sun doesn't look like it went supernova, probably should've phrased that differently.
Also remember the Heart of the Black Garden? That thing was supposed to empower the Vex with paracausal abilities. With that they could theoretically be the strongest enemy in the series. However, without it they have to stay in 5th place.
Assuming Panoptes found a way to destroy both the Light and Darkness would mean that the Light could have lost, but then the Darkness would get destroyed by the Vex, or vice versa. Hell they could destroy each other and then the Vex swoop in.
Also you don't know, if every ship of the Darkness was here then a supernova (assuming they don't have ultra-powerful shields or instant teleportation) would absolutely wipe them out.>