You are right that it's not enough to have ToS; the users should actively accept them. But what was plain wrong about my post? It said typically this is how it'

You are right that it's not enough to have ToS; the users should actively accept them. But what was plain wrong about my post? It said typically this is how it's supposed to work, in which the wiki has a right to change its licensing. Not that TVtropes ToS is like that or that what they did was right. If the only provision of the ToS that you're accepting is that you are over 13, then the wiki has no rights to even distribute your content under CC-BY-SA. So the conversion to NC isn't even relevant. And in any case, you own copyright to anything you author, unless you expressly transfer them to someone else in exchange for some sort of compensation. Absent that, the blogger of OP is fully able to release his work under any license he chooses. And he did that on his blog. So what's wrong?