Snohomish County has seen a massive influx of immigrants from many different countries in the last 15+ years. Each culture brings their own churches and communal norms with them. Many start churches as a place to gather. It's difficult to find statistics on churches per capita in a specific county but having grown up there (and I mean *right there*) and having lived all over the country since then, I don't think the Edmonds/Lynnwood/Mukilteo area is any more religious than anywhere else.
As for homeschooling, Edmonds School District has it's own Home School Resource Center with an enrollment of about 500 K-12. If that were a K-12 private school, no one would think twice about it or call it weird.
https://en.wikipedia.org/wiki/Edmonds_Homeschool_Resource_Center
http://www.greatschools.org/washington/edmonds/3480-Edmonds-Home-Resource-Center/
Washington State as a whole is one of the most non-religious areas in the country. Its especially prevalent the Puget Sound area. But there are still plenty of religious folks and religious immigrants who start small churches to create community. But compared to the South, for example, we have far fewer people who affiliate as religious.
Homeschooling is NOT uncommon here at all. WA has one of the best homeschooling laws in the country and particularly in Snohomish County there are huge numbers. Now, being an affluent area, Edmonds/Mukilteo probably has more parents who are able to send their kids to private school before homeschooling but I grew up as a homeschooler and have homeschooled my kids for 6 years in Snohomish county and I can tell you there are many thousands of us. Many homeschool through school partnerships, most, like us, are non-affiliated, some do online academies. There are many options. But homeschooling is not weird or unknown here whatsoever. I suspect its one of those things that people just assume you public/private school until you bring up that you don't. Unless you're in the community you don't really realize how very common it is across all sorts of households, ethnicities, education and income levels.It definitely doesn't correlate to sheltered or unworldly. Sure, a few people do completely lock their kids down, but that is mainly a stereotype, not the norm.
Tyler was likely an intelligent young man who could figure out how to stay hidden if he wanted to. I doubt someone is hiding him... he could easily be hiding himself in many public areas. He may have completely left the area for all we know. When I ran away I flew to Idaho. All set up and arranged myself at 16, including buying tickets over the phone, arranging cabs, etc. I was out of state within 5 hours of leaving my home. Had I not felt sorry for my parents and left a note they wouldn't have found me until I wanted to be found.
To me, other teens from the area missing right now is a non-starter. Teens run away all the time. This is a pretty densely populated area. We are especially aware of them now because we are aware of Tyler. But its not uncommon for teens to go missing and show back up.