Would Trev get in trouble? He's not a dev or nintendo employee.
I don't think he could. I think, as a journalist, he has certain rights that would protect him. If there was some kind of note on the document he was shown that said "information is not to be distributed" or whatever, I don't think he could get in any trouble, but I wonder if Nintendo could send a fairly threatening email. Perhaps there's something small they could take legal action over. Not sure. Since he never showed the document, I really doubt there's much anyone could do, but I'm really not knowledgeable about legal matters, unlike the people Nintendo employs on their legal team. Nintendo could also have asked nicely, I dunno. *shrug*
It's possible that the source requested he take it down. The source's reasoning might be 1) Source regretted the decision to share it 2) There was trouble brewing at Nintendo and Source thought taking it down would help 3) Source was found out and told to have it taken down. There are tons of possibilities, and I'm only speculating about a few. I'm truly taking shots in the dark, and hopefully Trev will be able to shine a light on it.
Ultimately, the things I could see Nintendo getting upset about are the budget info being released, since that's typically very private, and the price drop plan, as that can impact sales. Everything else I can't imagine Nintendo would care about because, from what people have concluded, a lot of the mysterious games are likely, but unable to be confirmed, more localizations and we have no way of knowing anything else about the remaining others.
There's also the chance that it was fake and Trevelyan9999 took it down upon realizing that, but I imagine it would have had to have been a pretty elaborate ruse for the identity of the source to be identified and verified by two different people (Trev and the mod) and then for them to deliver fake info. It's very unlikely, but if this somehow were the case, we'd probably see this thread closed eventually.