Technically Damore did not do the company wrong. He posted on a private, internal discussion board at Google. Someone else leaked it to Gawker, doing the actual

Technically Damore did not do the company wrong. He posted on a private, internal discussion board at Google. Someone else leaked it to Gawker, doing the actual harm to the company. Also, his memo is concerned with what he believed potentially illegal practices at Google and so he may be protected by whistleblower laws. Yes employment is at will in the US, however the legal analysis I've seen indicates he has above average chance of winning a suit against Google, if they don't just reach into their very deep pockets to settle out of court. He may walk away from this a millionaire.