Yes, but DF dwarven lives are commodities one can obtain easily. Casualties on the Martian colonies would be difficult to replace, and also demoralizing to us while boosting the morale of the Terrans. Rube-Goldbergian devices are also wastes of resources. Overall, when waging a war (ESPECIALLY against a massively superior foe) or starting a colony (ESPECIALLY in an unknown type of region where any mistake has a high chance of death), you can't afford any kind of waste...and waddya know, our proposed project fits the ESPECIALLYs of both.
You're forgetting something. Do you think anybody would want to fuck with a force that:
a.) can field stuff like literal swords of Damocles (i.e., POINTY SPEARS AIMED AT OUR ENEMIES' HEADS) and gigantic colonies and so on with ease?
b.) and this is the important part, would anybody dare fuck with a force that can so willingly throw away the lives of their countrymen just to ensure the death of their enemies?
We are talking about total war. When worst comes to worst, we will have to make decisions that would ensure our superiority. The Earth Federation will not win. Look, I may have been watching Gundam a bit too much, but I have a point here, dammit! We'll just throw a few colonies at them; aim it at their capitals. The force of the impact will destroy them and cripple their morale greatly. They'll be all, "oh my god! they're willing to do
that? Game over, man!" and just surrender. How do you propose we fight anyway? Conventional means? Spacecraft? No. We have to escalate the war as quickly as possible until we cross the threshold and they lose their appetite for destruction. We win by hitting them where it really hurts: their morality. We are SPACE, dammit! SPACE DOESN'T LOSE.
If you're so concerned about something like "the value of life", then
fine, we'll evacuate the colonies first. Not as fun, but if it pleases you, sure. But I'm still proposing that we throw down colonies.