Earlier quoted context omitted.
It seems to me using a plane would be a bit of a slippery slope then. A commercial airplane's main purpose is to access somewhere beyond one's own community, and the experiences of international travel to a foreign land will change you (not to mention, I'm curious why they would target the Philippines vs any modern local American city). But people will do as they do, I suppose.
They aren't opposed to an experience changing them. And most things are guidelines to make choices, not absolutes. In this case, going on a mission was a higher priority, and the most effective way to get to the target was via air travel. If there was an alternative then they would take it. This decision matrix isn't unique to the Amish -- people do it every day. For example, I want to save money. But I also want to…
It's not so much the experience change I'm pointing out, rather that that will bring foreign influence from outside (and obviously foreign influence has occurred because they are using tractors and diesel from the other comments.)
And if we're considering a decision matrix that tries to minimize outside influence, that still doesn't explain why the Philippines vs any where in North America, really.