Not the author, but maybe some thoughts:
‘> These freebits also have to be quantum in nature. Why?’
Maybe the author is assuming there are no elements in the universe that don’t follow quantum mechanics?
‘ > Suppose you want to track back the chain of events that led to a specific incident—something interesting in a physics experiment, or a chicken crossing the road. For some incidents there will be a chain that goes all the way back to the original freebits. For some incidents? Shouldn't literally everything have a chain going back to the original freebits?’
It seems like everything should have a chain of causality back to some thing. Except there has to be at least one uncaused causes, or else it’s just an infinite regression and not meaningful.