Hmm, this take seems too all-or-nothing to me. (I made a similar trip with similar prep - bought the bike a month before going.)
The first chunk of the trip is very civilized, and you can use that to build skills before you get out in rural Utah.
If you have some experience with dry-country hiking, you understand about bringing water. That's the main threat. Most of the other mishaps you can think of are just inconvenient/unpleasant - "made poor time, got stuck at dusk in the middle of nowhere with only the snacks in my panniers, and had to camp by the roadside".
The author did prep for some other gotcha's, including having safety gear and doing some physical training in advance.
I'm a long distance hiker. As far as water filters go, the Sawyer Squeeze is a great choice. But—and this is important—do NOT get the Sawyer Mini to save weight/space. Get the full-sized one; you won't regret it. I've tried both and the Mini version simply does not have enough through flow to not be annoying over the course of a major trip.