I think Earthworm is pretty accurate with his initial post. I think it's definitely a bit problematic to immediately conduct another vote after it was voted to not be banned, and I'd go as far to say that the threshold which was used was too low if anything, not too high. A council vote should have a higher threshold than what it takes for the general community; if it's a contested decision, it's probably best to not have a small group make the decision for the larger community. Council bans should probably be something unanimous or near unanimous, not highly contested between a small group of people that make the decision for the larger community. I think this can be tackled a bit differently by things like the general public overwhelmingly being in favor via a community survey or something of the sort, however. Don't really know what the best way to convert the general public's opinion there into a Council vote, but I'd argue a 60% threshold for something that didn't get any kind of public input is a bit sketch.
ftr I'm not trying to criticize the council for this, it's common practice for Council votes to have the same threshold and I've been responsible for many votes this way, however I think it's probably a good idea to change.
With that said, I think King's Rock is a bit of an outlier for this situation. It's not a Pokemon or something similar; it's an item that the general public very clearly believes is problematic and needs to go, and it was voted on without any form of quantification for public opinion beforehand. Like Lilburr said, the issue at hand was decided upon by a fraction of people that play the metagame out of a playerbase that I anticipate to be overwhelmingly in favor of banning King's Rock. I think Earthworm is right that the Council's role isn't to submit to the public's every whim, however I do not think their role is the absolute decision maker. If the general playerbase is, say, 95% in favor of banning King's Rock, but the Council vote was 4-3 in favor of banning, should we keep it not banned? I don't believe this is the right way to go about things, and that ultimately the general public should be involved with decisions as often as possible. The council should absolutely try to manage the tier in the way they believe is best, and I believe that the individuals who voted to not ban it believe that they are. However, I think an overwhelming public majority, like the one I anticipate from the ongoing OU survey, holds more weight than the Council's dissenting opinion. I also do not believe it to be fair to expect the OU Council to want to hold a public suspect test for an item such as this, as it's not common practice and something that was probably more straightforward to handle.
While I think the need to ban Bright Powder and Quick Claw is really not well justified or necessary, I do support banning King's Rock. Pokemon is filled to the brim with many different forms of RNG, and I believe it's really narrowminded to try to justify that all the "luck" items are that much worse than a bunch of things that every Pokemon already has available. See things like Sand Veil, Serene Grace Pokemon, Static, Flame Body, Effect Spore, Scald, Hurricane, and even Triple Axel. However, King's Rock is different. King's Rock on multi-hit moves is so much more RNG-dependent than the aforementioned things, as it has a way higher chance of occurring, and when used on something like Cloyster, a flinch from King's Rock Cloyster can very easily mean the game is over. Cloyster is a Pokemon that gets a multitude of chances to setup in this tier and anyone that has played or watched any minute of OLT Laddering will know this. The most common Pokemon in the tier is the perfect setup bait for it, and it also has superb physical bulk and can find an opportunity to setup vs many other Pokemon in the tier. Any argument saying "just don't let it setup lol" are extremely bad arguments against banning it, because if all a Pokemon needs is one free turn to win any game on the spot, it's definitely broken. Do you want to free Xerneas just because it needs to setup? King's Rock is not "broken", as 40% to win a game is obviously not good odds. However, this 40% is not something that can be prevented in a large amount of situations, and to want games to come down to this simple thing is asinine.
As an aside, has there been discussion on voting on Cloyster rather than King's Rock? I have not thought about this stance too much, but I don't recall seeing any discussion. I think there's a fair argument in favor of it due to the fact I do not believe anyone would argue that King's Rock Cinccino is problematic for the tier; it's really only the combination of Cloyster having a guaranteed 5 hit move without making contact, the best setup move in the game, and also the ability to use King's Rock that makes it problematic. I don't really believe King's Rock on other Pokemon fall under a level that deserves action. However, I think it gets into a very gray area; voting on a Pokemon because it's "uncompetitive" is a bit awkward, and I don't know if everyone who wants King's Rock banned would really say that Cloyster is broken. On top of this, if another Skill Link Pokemon gets introduced with any form of setup or incredible stats we could be back to the same discussion. This is just a hypothetical, though. Uncompetitive things have always been tackled differently than just plain broken things, and I think it's perfectly fine to want to ban King's Rock rather than Cloyster. See: Moody Pokemon, Sand Veil in old gens, Swagger, and so on.
Ultimately, if the current OU Survey has overwhelming results (say 80%+) in favor of banning King's Rock, I think it would be a bad decision to not do so.