The Amish always vote Republican. It sounds like the author is clueless about even recent history.
I think he means that traditionally, most Amish haven’t voted in presidential elections at all.
Historically only a tiny percentage have voted.
For decades, the Amish have declined to vote – that could all change (and it's because of milk)
It is unimagineable that anyone who lives a lifestyle that is incompatible with the regulatory state, and the existence of which is seen by the regulatory state as a threat and provocation, would vote either democrat or, spit, Bush style compassionate RINO.