It is. Who precisely is "We"? I personally never said 0x123457890 was the OG Bored Ape. What if I band together millions of people and determine that 99x12345678 which I own is actually the OG Bored Ape. How can you stop me? Isn't that what OpenSea is effectively doing...providing a centralized trust system to say "well of course everyone knows OpenSea is the source of truth because everyone knows it and the consensus is on the blockchain"
I mean, that's exactly how decentralization works. I can't stop you by design. Simply put (and for better or worse), it's tyranny of the masses. If you can do that (get everyone to treat another contract as the real Bored Ape contract), then you've effectively "forked" -- this has happened a couple of times in BTC and ETH.
Consensus. We all agree that 0x123457890 is the "Bored Ape" contract, so everything spawned from it is a "real" Bored Ape. It's kind of how we all agree who the real "Picasso" is. This isn't really controversial or hard to grasp, and imo Vitalik's article just muddies the waters.