I mostly agree. The moon is definitely doable. I don't really know why you'd want to do that (really, what problem is that solving? what new things are you learning that you can't on earth?), but it is definitely attainable. Just horribly expensive for what it is: a bunker in the middle of nowhere that has no strategic purpose and only contributes a little bit to science or engineering. I'd much rather see that money spent on some real science, or perhaps on creating habitats in certain places on earth (oceans, deserts, ...).
The biggest problem though with this discussion is that the idea of sending humans off planet as a type of backup for humanity is really flawed. That would work, if we had the technology to send many and make them self-sustainable. If you put a colony on the moon, anything below a couple million people will not be self-sufficient (think of all the branches of industry, all the technology it would have to replicate, just a no-go). In fact, a good estimate I saw put it at about 100 million people, for our current level of technology. And you wouldn't even have the abundance of resources that we have here on earth, making it so much harder still.
The truth is, if earth goes, whoever you put on the moon is screwed just as much as we are. So let's try not to make that happen.