They could also find a few places where synonyms can be substituted without sounding weird, a few places where a comma is optional or can be replaced with a das

They could also find a few places where synonyms can be substituted without sounding weird, a few places where a comma is optional or can be replaced with a dash, ... much more likely to survive a journalist doing the responsible thing and retyping the e-mail. For example: His {stated, claimed} motivation {is, was} that he {wanted a promotion that he did not receive, did not receive a promotion he wanted}. {In light of, Given} {these, his} actions, not promoting him was definitely the right {move, choice}. This can be detected by people comparing two e-mails, but the unicode trick can often be found just by looking at one of them, so I wouldn't say one is more stealthy than the other.