Along with many other accounts, it's locked due to being affected by the 2015 data breach and then sitting inactive for a long time. If he wanted to access it, he'd have to go through the Recoveries team and provide proof that it was his account. And it's not immediately clear to me what proof he would use, since the account never posted a Bitcoin address to use for signing a message, or anything like that.

Also, since altoid directly posted a link to the Silk Road, I would guess (not sure) that Ulbricht argued in his court case that it wasn't actually his account. Maybe he wouldn't want to contradict his past testimony?

So he could regain access to the account and post something, but I don't think that it's very likely.