If any famous people involved with creating the 'real' Star Trek were to play STO, announcing their presence and true identity would be the worst ever thing to do.
I know some fantasy and comics writers who did.
I don't think it's a secret that Mercedes Lackey and Gail Simone both played at launch, as did a number of comic book people. (Gail was more obvious about it but Mercedes was a longtime Cryptic fan.)
The game, at launch, wasn't really to either of their liking and I don't think they've come back.
I was in Gail's guild in City of Heroes, along with Misty, Howard Porter, Mark Waid, and a few others. We had a "blink and you'd miss it" rivalry with Geoff Johns, who was in the Marvel comics supergroup.
I did talk briefly with Peter David about STO back at launch. He was intrigued by the use of Mackenzie Calhoun and said he planned to write a blog piece about it but never did.
Odds are most of these celebrities famous to not so famous... They have better things to do than sit around tweeting, IM"ing, tumbling or whatever... Its probally some 12 year old wanting to see some nerd rage when they figure out its not really him...
Next thing you know everyone is going to ask him to have him make a video of him picking up the newspaper to prove his identity... ROFL
Twitter is different, mainly because it's quick and easy and can be done on the go.
If congressmen can tweet in the middle of speeches then, yes, I think most celebrity tweets are from real celebs.
There are only a handful of celebrity twitter accounts I think are run by interns.
Now... You know who's opnion I would like on STO? Aaron Eisenberg aka Nog. He's a fulltime MMO gaming podcaster last I heard.
His dialogue explaining it was. And I suspect that's because a TON of people cameoed. His scene was supposed to be about him asking Ashley Judd out but she was one of the people who couldn't make filming and the replacement they got for her didn't have the same impact in that scene.
Wesley did pop up in a live Trek event as the Chief Engineer of the Titan.
In general, the film folks and producers seemed to support the idea that a more mature Wesley was back in Starfleet while the references in the books all dumped on that idea and made it a big joke about Wesley showing up to the wedding naked and putting on someone else's clothes.