I know it sounds weird, but in prehistoric times, people could do a lot of fighting themselves with basic weapons. There wasn't really an industrial base needed to create materiel for war. Of course, in real life, this hasn't been the case in a while, and it probably won't be the case in 2200 unless we nuke ourselves. But even in modern times, as long as someone is on the same landmass as you, you could theoretically walk up to them and hit them. It might not be very effective, but enough people armed with ordinary objects like golf clubs or baseball bats could pose a threat.
However, now that organic Ships exist in the game, we could imagine a spacefaring society that can just go up to people and hit them in space. Perhaps, the members of this species can come together in large numbers and somehow merge into a spaceship. It could be that the reason they didn't do it before 2200 may be that their population wasn't high enough, or maybe they could go to space but didn't have faster-than-light travel.
An Empire with Pops that have this Trait would still be able to make Ships normally, and it would usually be more efficient to use those Pops to grow Food or make Alloys, but sacrificing some Pops to make Ships would be handy in a pinch against a superior foe even if it wouldn't be sustainable long-term. I think the Components of the Ship should probably still have to be paid for; one can't just get out of paying Minor Artifacts or Dark Matter, but there could be a discount to that as well, and the building process would be much quicker. For the actual user interface, it could be similar to the tab on Starbases where you can make Armies.
As a secondary suggestion, if you're an Empire with Biological Slaves or Undesirables, and you have some Voidworms, you could also just feed your Slaves or Undesirables to the Voidworms to allow them to reproduce; this would not require the special Trait as the Voidworms' biology takes care of that, so it would be available to many more Empires. This would be a nice way to get something different out of Purged Pops. The user interface would be similar.
However, now that organic Ships exist in the game, we could imagine a spacefaring society that can just go up to people and hit them in space. Perhaps, the members of this species can come together in large numbers and somehow merge into a spaceship. It could be that the reason they didn't do it before 2200 may be that their population wasn't high enough, or maybe they could go to space but didn't have faster-than-light travel.
An Empire with Pops that have this Trait would still be able to make Ships normally, and it would usually be more efficient to use those Pops to grow Food or make Alloys, but sacrificing some Pops to make Ships would be handy in a pinch against a superior foe even if it wouldn't be sustainable long-term. I think the Components of the Ship should probably still have to be paid for; one can't just get out of paying Minor Artifacts or Dark Matter, but there could be a discount to that as well, and the building process would be much quicker. For the actual user interface, it could be similar to the tab on Starbases where you can make Armies.
As a secondary suggestion, if you're an Empire with Biological Slaves or Undesirables, and you have some Voidworms, you could also just feed your Slaves or Undesirables to the Voidworms to allow them to reproduce; this would not require the special Trait as the Voidworms' biology takes care of that, so it would be available to many more Empires. This would be a nice way to get something different out of Purged Pops. The user interface would be similar.