He's describing what I have experienced using a legit TBC beta download from the official WoW Beta site and a sandbox mod that took 5 seconds of googling to find. I think short of posting movies, boss walkthroughs and encounters, he won't get any trouble for saying he's enjoying the game a lot on a visual level. That said, it's prolly not wise to announce you're a TBC beta tester on a public forum with a private messaging system, unless you enjoy swamping through 50 mails asking "OMG INFO PLX".

ps: the new zones ARE breathtaking.

The content of his post indicates certain things which, as far as I can tell, aren't possible in a sandbox: He describes mob placement in Zangarmarsh, and claims that a certain area was supposed to be closed because it was unfinished. Neither of those things would happen in a Sandbox mod (I suppose a sandbox could spawn mobs, but why would he complain about silithus bugs, if that were the case?)

At least one Blizzard dev reads (and posts to) this forum, and his profile is filled out. I suspect someone's got themselves banned from alpha.

Honestly, they guy has just said that the new zones are beautiful, I really doubt he'll get in trouble for that. He didn't even describe them.