A question: does the ~$0 vs $27k include living expenses?
I went to a small tech school similar to NMT, but in a major city, on a full-tuition scholarship. My parents lent me money for any living expenses I couldn't cover out of summer internships and PT research and tutoring jobs, which ended up being around $25k by graduation (mostly: housing expenses). I absolutely loved the education and opportunities I received for $0. But I also knew people at my school who absolutely hated it.
A small school can be really great...especially if you're more on the shy side; if you might be intimidated for the competition for opportunities (student leadership, undergrad research) at a large school; if you are drawn to the culture and find like-minded people and a sense of community there; if you are there for your education and prefer lots of professor/instructor/staff attention to relative anonymity and extensive bureaucracy; if you are willing to put a lot into your experience; if you are willing to get creative and get people together and start something rather than being a passive consumer of college. Doesn't even have to be big/official. We had a massively successful casual sci-fi movie night with just a large group of friends.
On the other hand, if you don't fit with the small school's culture you might have a hard time (people who came to our tech school with plans to party? Weren't really satisfied). If name recognition/networking is important, you are likely out of luck there (big state schools have proportional alumni networks..."Oh, U of X? I/my sibling/my spouse/my parent/my uncle went there!). If professors' involvement in cutting-edge research matters more than their teaching skill or personal attention, the larger school might be for you; not that ALL profs at large schools suck but in my experience smaller schools put a lot more emphasis and faculty time into their teaching. This is probably not an issue for CS, but: if easy availability of software, a large library, an open-to-all workshop or maker- space, or nice gym facilities is important, those may be easier to come by at large schools who have more resources and more demand (you can check on these things on a school-by-school basis though). If you have significant uncertainty in your major, a larger school has more options for switching (without transferring).
Regardless of the school, I would estimate that typically 90% of student life takes place on or around campus. It's classes and work and homework and dinner and projects and gym time (hopefully) and sleeping in on the weekend and yes probably some parties/beers and some school events--conferences, career fairs, football games, LAN parties, etc. And as for the other 10%...if he really loves CO he can organize some roadtrips there (spring break, early/late summer, winter ski trip, etc), or try to find a summer internship or co-op in CO. Or eventually get a job there!
I guess, to me, paying $100k+ to go to CO for college because of the scenery/surroundings is a lot like the idea of getting a tricked out 4WD SUV because you go up to the mountains twice a year for 3 days apiece where that functionality *might* be useful, and then driving it to work and errands the other 359 days of the year. I would totally push him to take the free education, and if you are able, you could sweeten the deal by offering him a $1-2k travel budget/stipend so he can actually take advantage of the savings he is creating (since it's hard to emotionally appreciate the gain of not taking out loans in the moment...). I say this having ultimately gone to the big state school in the middle of a cornfield for grad school: it may not have been my "scene" as much as the smaller school was, but with its other benefits I would totally have advised my past self to go there if it was free. Since it wasn't, I'm very, very happy with my undergrad choice.