Basically he is saying that Proof-of-Stake does not work without some element of human subjectivity to compliment it and calls this compliment “weak subjectivity”.
I am thinking Sunny is aware of this and this is the reason why centralized checkpoints still exist.
Vitalik defines a new scoring mechanism called exponential subjective scoring which I could not wrap my head around, can anyone provide any insight?
The “Exponential Subjective Scoring” is just a way for nodes to rate the validity of chain forks. The longest chain (in terms of time) wins. Whereas in Bitcoin the longest chain (in terms of computational effort) wins.
I have to say Vitamin B is long on makeing up new terms, but short on programing/algo cred. Sorta the opposite of satoshi.
The premise there is nothing at stake is wrong. You are free to mine as many merged mine coins as you wish, with one processor, similar to peercoin can mint for as manly other chains, it does not stop you being in the peercoin chain or not.