I think the good/sorta/bad feature poses an ethical problem, because it is anonymous and collective.

Christianity (and Roman Catholicism) teaches that we should not blacklist our brothers and sisters who do "bad" things. The Bible says : "if thy brother shall offend against thee, go, and rebuke him between thee and him alone" (Matthew, 18:15). 

So the Bible teaches us not to remain anonymous when we judge that our brother or sister did something bad.

Christianity teaches forgiveness and mercy. How can the people "unbad" a post previously judged as "bad", which they want to forgive ?

The good/sorta/bad feature trivializes the notion of judging people as "bad", whereas Pope Francis, for example is famous for saying "who am I to judge" ?