That bothered me. Just because someone lives in Germany/Austria for 20 years, they wouldn't lose their native English accent when speaking English. Just as when someone from Germany/Austria moves here, they don't lose their ability to speak their native tongue in the original accent. Instead, they tend to speak English w/a German/Austrian accent.
shareMy take was that he changed his dialect on purpose, in order to fit in with his new identity after deciding never to return home. Remember, at some point after his injury he changed his name and identity to an Austrian. Not unheard of i real life to intentionally change your native accent on purpose--Cary Grant and Mel Gibson come to mind.
shareI'm not sure Cary Grant is a good example. His natural Cockney accent shows through clearly, although he tried to dampen it somewhat. Hugh Laurie would be a better example. He has a strong English accent, but was able to lose it entirely in House.
A person's a person, no matter how small. -- Dr. Seuss