of the 6 person ceremony we have ZCash founder, ZCash technical advisor (Andrew Miller), ZCash CTO (Nathan Willock). My bad. 3 of the 6 (possibly +1 because one is still unknown). I mis-remembered. Arguably the person from NCC isn't conflict free as they were paid directly by ZCash.

NCC gets paid to do security audits, and getting paid puts their (very high) professional reputation on the line.

I'll admit I'm biased: I worked a bit with Zooko and Nathan (Wilcox), pre-Zcash, on some other security audits. My experience was that making the client look good is really not a consideration. Phrase your findings neutrally and informatively, yes; but you earn your rep by being as creatively nasty as you can at breaching the system.

Not to argue against evaluating claims skeptically -- just to state my most important disagreement.