I'd say you're likely in more danger than if you didn't say that, but people have to believe you as well. You see, most people would attribute him to being a wealthy eccentric. He'd probably be well spoken, and not talk random nonsense on some forum as well. If he genuinely came out and had compelling evidence, yeah he would absolutely be in more danger. His wallet owns somewhere around $10,000,000,000 to $20,000,000,000. If people knew who he was they could extort him or threaten him or his loved ones and force him to transfer some or all of it out. I would never come out if I were him, most other people wouldn't as well. The fact anyone says they are Satoshi is immediately suspicious, and most would dismiss it instantly.