I just looked over the whitepaper of Proof of Bitcoin Node:
http://spreadcoin.info/news/wp-content/uploads/2015/10/Proof-of-Bitcoin-Node-DRAFTv1-1.pdf
and can not find a section that describes how it is able to prove that a Bitcoin node is real and validating.
It seems to me from a brief look, this proposal ignores and does not address the most important part to PoBN.
This proposal is to use processing for non-bitcoin related data, to indirectly incentivize bitcoin nodes.
Though the overall premise is correct and this is a likely future, where nodes do processing for multilayer systems,
the proposal does not give an answer to how a Bitcoin node is proven to be deserving of such an incentive or whether
a Bitcoin node will remain necessary over time for this proposed system. For example, just as Bitcoin Miners created
specialized systems to become more efficient, these node processors may drop the Bitcoin Node aspect if they are not
bound correctly, resulting in PoBN as proposed becoming a new processing node only for the multilayer systems.