The email address is/was easily found by a google search. I don't think it was private information but I can see how it is 'personal'. It really depends on how Twitter defines "personal information".

> The email address is/was easily found by a google search.

It is now, it looks like it was not before: http://searchengineland.com/nbc-olympic-executives-email-was...

That article does a poor job proving that you could not find the name before with a simple google search and/or some basic deduction.

Another theory is that his account was suspended for criticising a corporate partner, and the "personal details" is just an excuse.

Yes - if it's not available publicly.

No, if you can guess it (e.g. [email protected]).

It's still personal if you can guess it. For instance, you might be able to guess someone's GMail username by their Facebook vanity URL or their Hacker News username. That doesn't mean you can post their email all over the place.

If it's not posted publicly by the person, it's private.

Whether it's "personal" is not relevant -- Twitter's policy prohibits publishing information that is "private and confidential."

Since his corporate email address is neither, it would appear Twitter's grounds for suspension are quite weak.