State tax filing

So we lived in Montana for school part of 2018, and then moved to South Carolina for my work. His state of residency is Ohio, and his only income was from being a Marine Reservist. So I'm filling his state tax return as a nonresident Ohio (Ohio taxes were withheld but we never lived there in 2018). However, all of his income was earned in Michigan where he was drilling. So there was a question about earning an income in a neighboring state to Ohio, and I wasn't sure if our situation counted in this category.