People are assuming that they did not die because the report of US citizens who died outside of the US did not mention them. IMO this is kind of a weak justification, bureaucratic mistakes are not that uncommon. I that people are missing the point with the whole situation, they important thing is that they were heavily harassed for years, so much that now the free software and emulation communities ended up losing one of their brightest members.

Yes. Multiple people who knew him have confirmed it a long time ago.

There has been nothing official no. marcan42 is the only named source who ever confirmed it I believe.