Thanks for the article and response.
There is one misstatement there. You state that
“The more PoP publications reference a given VBK block, and the earlier these appear on the BTC blockchain, the deeper is the referenced VBK block anchored.”
PoP transactions cannot appear “earlier” on the BTC blockchain. Their appearance is in the mempool the moment they are published. Their tx fees then cause them to either be included in the next BTC block or not.
Then you state
“ Should there be a fork (i.e. two competing chains) on the VBK network, then the chain whose first few blocks (counted from the forking point) are anchored deeper becomes the winning chain.”
This is 100% correct, however it has to be viewed in sync with the market bidding side of the matter. PoP miners will continue endorsing the one chain they believe is correct. In essence, the correct VBK chain should be the one with 51%+ of the weight of PoP miners.
You also describe a way to do a Finney attack on VBK blockchain, which needs to be assisted by PoPing the secretly mined blocks. However, due to the above, one would have mounting costs associated the longer they attempt this, as they would have to compete with all current PoP miners on the main chain. You would therefore need to 51% attack the PoP mechanism as well to gain a majority there. This means using about 5 BTC per day on transaction fees at the time of writing.
I like the rest of the article and it raises very valid concerns.