The author apparently thinks that users won't reveal their view keys in public.
The author (me) does not think that.
But does, apparently, attempt to publish pragmatic improvements in technology, without raising his expectations of others to the point of being discouraging.
As you do not publish your design, I can only respond with wild imagination. Your bearer coin might do well to hide values in its off-chain components; whether this specific technology may be useful for that, I do not know. I can imagine that the pure hash on-chain re-orgs are going to be possible and fun. Lamport signatures or much longer keylength for quantum computing. Of course, when people are Sybil nodes, and your spend is to an under-cover agent, and the courts shall accept the agent's circumstantial proof as sufficient and ignore the [lack of] math, ... oh what a world.
Again I appreciate what you have done with the Sumcoin whitepaper. For one, you made it much more intelligible than the unpolished brain dumps I had read from Adam and Gregory. Also I prefer your technical writing skills compared to mine. And perhaps on the same block chain some coexistence of Cryptonote's rings (with equal denominations) and this new homomorphic encryption (with unequal denominations) might be the optimal solution. We should probably discuss that at some point and maybe you and others are already doing that.
I don't think my design removes the block chain, rather I argue it just moves non-scalable part of it and alters the trust model to something that isn't a lie to ourselves. It is a similar argument that Gregory (Jorge) makes but inverts the construct and puts more decision power into the ends of the network (which is why I presume you use the term "bearer"). So I could see your work being incorporated. One my goals is to be agnostic to the transaction model because my weakness is I am only an autodidact on the crypto-math, thus I want others (such as yourself) to have the freedom to innovate there without needing to market a new instance of a consensus algorithm (i.e. maximize the division-of-labor and let each focus on his/her strengths in a separation-of-concerns).
I believe quantum resistant rings, PKE trap doors, ZK exist and we just need to reformulate them into these new constructs. Hopefully we can motivate some research perhaps with calls to action and/or financial incentives.
Yeah I agree we need anonymity that is mathematically reliable, because the math-inept society won't forgive us for being math literate about plausible deniability.