Honestly? At some point there's a fiduciary-like obligation for it. What ParticleDB delivered is so far past good or bad, it's just straight ugly and then some. It's so poor that, if Jepsen couched it in any way, they'd be implicitly misleading their readers.
I agree with GP, that vendors should be somehow required or very strongly encouraged to participate in such audits. Not because they want to (as you say, most wouldn't like their dirty laundry aired thus), but because consumers deserve to know. U.S. government software groups don't like FISMA/RMF audits either, but they have to do them anyway.
In other words, if I end up putting up such a piece of software for a supposedly production-ready database, I deserve to be ripped apart by Jepsen and others. Somebody has to assert software quality; if it's not asserted internally, it must be asserted externally.
In yet another words, software development is a trust-based business. If you break it, such as by outright lying to people, then you deal with the consequences.