It doesn't matter if the algorithm is known, or unknown in a distributed index, the fact is, any ranking algorithm will be vulnerable to poisoning attacks.
Let's say you have a completely distributed search index with no ability for a central authority to curate. An attacker wanting to sway the US election would simply flood the internet with fake sites and link farms, designed to attack the weaknesses in a publicly known algorithm. This is in fact, substantially more likely than Google modifying their own system to favor a candidate.
What this basically means is he who has the most compute resources wins. Powerful entities could still manipulate the result just as anyone who owns more than 50% of the hashing power in the blockchain can dictate it. Dedicated campaigns can do it too (Santorum anyone?) Any coalition or entity with greater resources than the opposition will have an outsized voice.
You're positing a decentralized system absolutely immune from collision or resource constraints, in all likelihood, the systems deployed would have huge compromises that can be manipulated as easy as a Google Bomb, only with less ability to mount a defense. That is, an open index and known algorithm would likely be WORSE at defense against manipulation.
One only needs to look at how long it took to develop defenses to spam on USENET/UUCP/NNTP and SMTP. Even today, the defenses are not perfect, and that's after 20 years of sophisticated development.
The reality is, if you commit a crime that's in the public record, if you're a felon, or had judgements against you, and your employer is going to discriminate against you, then they will find the information. How the hell do you think this worked before Google? You think background checks for job candidates only started when Google launched? The government, marriage, police, and civil court case databases are all public. If I want to find out if you're a criminal or a cheat, I don't need Google.
Your argument that I should 'dox' myself if I feel people shouldn't have a right to retract information from the internet doesn't make any sense. It's precisely because I don't believe you can ever retract such information that I don't post my sex tapes with Kim Kardashian. If I knew I could censor whatever I want, then I'd feel free to dump all kinds of information I don't want to get out.
If someone decides to spread your info on the internet, censoring Google won't save you. People taking revenge carpet bomb information all over many resources like Twitter, Youtube, Facebook, Twitch, Wikipedia. Ask the women harassed in the GamerGate fiasco if the biggest issue was Google searches, or social network spam. Have you not seen Encyclopedia Dramatica?
IMHO, if you want to deal with discrimination over knowledge of your public records, pass anti-discrimination laws. Don't rely on security-through-obscurity. If you're living a lie, sooner or later your workplace will find out.