Interesting. He said at the reunion, as I remember it, that "Henrich" was his name, as the Kolbs were Plaatdeutsch speakers, and would have found the High German "Heinrich" awkward and pretentious. This was in summer 2007. If I remember right (correct me if I'm wrong), the book was already published by then, so I guess that must have been a realization Dr. Ruth came to after publication. I'd like to contact him to clarify, but can't seem to find contact info for him.
That was in regards to this man's grandson who immigrated, but I would think the standard Plaatdeutsch name wouldn't have changed in a couple generations.