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.
Using actual colonies, even evacuated, is a waste of the resources used to make the space station, which likely includes valuable computers and life-support equipment and such. Much easier, and just as effective and terrifying, to toss an asteroid larger than that which wiped out the dinosaurs onto Terra. Or, heck, at sufficient velocity even a satellite or something can be devastating.
Ok, compromise: we make dummy colonies. They look like colonies, and when people from the decadent imperialist Earth Federation look at them, they think they're colonies, but actually they just house the shit-tier members of our glorious Martian society. Meanwhile our actual colonies are well... colonies.
Look, asteroids just don't have the same psychological impact. "Oh, boo hoo, they're throwing rocks at us. How scary. Nuke them." isn't the same as "Jesus Christ, man! They're willing to kill their own people! Clearly they are in the right about this. Let's just give up." With these dummy colonies, not only do we ensure that our enemies won't dare incur our ire, but we also get rid of useless space migrants, which, I'm sure, is something we're all familiar with.
Okay, for one, psychological attacks like the one you propose are generally called terrorism, and generally do not have the intended effect. Usually, instead of breaking their will to fight, the terroristic attack actually redoubles the enemy's will to fight. It just pisses them off.
For two, we would be expending a hideous amount of time, effort, and urists to be hollowing out space rocks for use as habitable areas when we are just going to throw them at earth anyway. Why not skip the expensive part and just throw them at earth?
For three,
we still haven't discussed how we are going to deal with the tripods. How are we going to accomplish anything when we're getting death ray'd every five seconds?
I don't like being mean, so I've been avoiding the whole situation for the sake of others, but I'm at the point where I need companionship or I'll go insane. 
. I tried to placate the crave with cheats, like allowing myself a soda on my birthday or when a friend was over. The crave saw my weakness though, and hit me hard. Once you quit caffeine you have to treat it like meth or something. Not even once and all that, heading to the rehab center after a Sierra Mist.
Hopefully not, but we'll see...