(Regarding the quote, we should remember that Dante lived in a time of extreme factionalism in Italy. In fact he spent many years in exile because his faction lost.)
(a) Passing neutral judgment;
(b) Refusing an interrupt / declining to invest marginal resources;
(c) Pretending that either of the above is a mark of deep wisdom, maturity, and a superior vantage point; and correspondingly that the original sides occupy lower vantage points that are not importantly different and not worth judging between.
As humans most of us rely on judgment of social status as one of the most fundamental ways to allocate resources and interact with one another. It creates an inherent bias when we grant the right of arbitration to a fellow human, because the privilege alone can elevate perceived social status, and possibly interfere with the granted responsibility.
The independence of social status from the right to arbitrate may be a measure of justness and liberty in a social group.
The difference between (b) and the second half of (c) seems unclear: what's the difference between
(b) (the decider) declining to invest marginal resources
(c.ii) deciding that the sides-in-question are not importantly different (presumably "not importantly different to the decider"; if not, please clarify) and not worth judging between (again, presumably, "not worth judging between to the decider"; if not, please clarify)
What's a scenario which is (b) but not (c.ii) and vice-versa?
The heavens, that their beauty not be lessened,
have cast them out, nor will deep Hell receive them -
even the wicked cannot glory in them.
In other words, what you're talking about is "I don't have the time to learn about this, so I can't judge." What Eliezer is talking about is "The circumstances don't matter, so I won't judge." There's a difference between a non-decision and deciding not to decide.