I would argue that the brand risk -- e.g. the risk of what ended up happening -- outweighs the legal risk.
That's not to say I wouldn't send it to a lawyer. But I'd do it with some hustle. Something like: "This is going out in 24 hours. Please comment ASAP!"
As Adam mentioned in so many words: most of the people pissed off about all of this are most likely right here on HN, and not even customers of Heroku. He mentioned most customers were not that mad about the issue overall.
