If your purpose was to explain how this solves a 51% attack from China, you have not yet succeeded.
> Nodes even define the PoW algorithm that miners have to employ.
Nodes change PoW algorithm and the old miners have expensive loud space heaters. They know this, which is why they didn't follow through on 2x. They knew that threatening that attack leads to one outcome : ruin.
It's a complex subject, sure. But I can't force you to understand how bitcoin works dude.
Satoshi's brilliant solution to the Byzantine generals problem of consensus is proof of work, not "nodes decide what code to run" precisely because nodes are vulnerable to sybil attacks.
-How would these nodes know that the 51% attack history is bad?
-A proof of work change is a hard fork, and these take months to deploy properly according to core.