No-true-Scotsman? I don't care, this one is valid: we're talking about someone who has some distant relatives in Scotland, but never set a foot there, hardly speaks English, and lives in China.
I do get that the proper threshold is not allays the same. The threshold of consent for having sex for instance, is very high (or ought to be). Still, some things I say over email are just as private as my dick.
People often do foolish things, it doesn't mean other people have a moral right to take advantage of them. (Alas, they sometimes have the legal right.)
By the way, in this case, it seems Microsoft spied on the blogger's account, to know where the leak came from. The leaker may not have used hotmail at all. While it's easy to notice cloud spying when sending from a webmail, it is a bit less easy when you send to a webmail: you're not even legally expected to have read the TOS. I mean, you still have to be careless to make that blunder, just less so.