No I mean 50% as in nobody can ever remove you from the 50%.
But to your point, who should decide who the misbehaving actor is? In what situation can you punish the network with only 1/3, as compared to 1/2 as with Bitcoin?
The punishment is baked into the protocol I think. If the protocol sees a node trying to create a fork that node gets spanked. I think all actions are signed now.
I don't really know, I just read one article about it this week. I've personally cashed out and checked out a long time ago.