I'm sorry but it was you who did not understand me. I was talking about how to build, not necessarily have to be of "snow". Nothing would stop me to produce ice blocks and build with them a simpler (K.I.S.S.) geometric shape (the igloo) and in a way that does not require the use of complicated apparatuses such as a 3D printer (you can use your own hands or a simple winch).
The concept relies on an autonomous lander arriving well in advance of any inhabitants in order to build their habitat.
I'm not saying that makes their approach any easier or harder, just that relying on an automated construction process allows integrity verification prior to sending anyone.
Also, so you're aware: the contest required use of 3D printing, not wrenches and hands. Again, not a judgement on which is better, but it's important to understand the constraints involved here.