by jsciv
As long as a player has a disc, they control the space, no matter what other ships are there. So even though you destroyed all of their ships, you did NOT take control. And when executing a build action a player may do it in a space with a disc.If you need a thematic rationalization: the fleet was defeated but the industry needed to build a new fleet wasn't destroyed so they can build a new one. :)
And no, the player with the disc is ALWAYS considered the defender no matter whose ships were there first.