I'd like to take a look at it tomorrow if no one else does. It sounds like he may be able to be categorized as a migrating ancestor and also Roll of Honor.
Coincidentally, I came across a situation in my own tree that I thought was really weird. Apparently, during World War II, seamen from Finland were brought to Ellis Island where they "deserted" and soon joined the US Army. Also, new men would sign-up. They also had Finnish names. I found this so odd, but perhaps it is the terminology that does not translate well? Anyway, this guy stayed in the US and within a year was a citizen. I think they were offering citizenship in exchange for serving in the US Army. I'll have to read more about it. From what little I did read so far apparently Finland was most concerned at this time period to maintain their sovereignty and initially were fighting the Russians with Nazi Germany, then they thought better of that and switched sides.