My two cents, since most of this has been covered:
I really don't see how people are coming to this "the Spirits have pissed off all the other Clans" conclusion. How so? What Clan's toes have they stepped on OTHER than the Star Adders? The other Clans were dismissive and ambivalent towards the Blood Spirits, not hostile...well, not hostile for the Clans, that is.
The Adders did rotate WarShips over York over the years...Tehuantepec was featured in the BattleCorps story "Tears of Blood", Sovereign Right or Absolute Truth (can't remember which) killed the Titanic over York, the Spirits destroyed Vritra over York, and there might be a mention or two that I can't recall at the moment. But it doesn't matter if the WarShips used were a part of the original bid or not, because the Adders didn't bother with communicating with the Spirits at all when they showed up to evac their people and start committing mass murder. They just did it. They threw any pretense of a Trial to the winds.
If we're all being honest with ourselves, the Adders did what they did on York as nothing more than petty, spiteful revenge. They can say whatever they want in their notes in the WoR book, but it was pretty clear why they did what they did. It's the same reason they came after the Spirits after the Viper Annihilation. They could've just let the Spirits leave and be done with them forever, but they not only came to finish what was started, they repeated York all over again, which pretty much underscores my reasoning for why they glassed York to begin with: revenge.
As for the Vipers, it should've been properly explained why the Blood Spirits would throw themselves so recklessly into their Annihilation when it would've made sense for the Spirits to use the distraction to further distance themselves from the Clans. This plot point made absolutely no sense, and not even Andrews' actions against them on Tokasha adequately explain this because this isn't even alluded to in the book. We're all just theorizing at this point.
It still makes no sense to me that the Coyotes were allowed to live despite literally betraying and selling out the other Clans, and the Scorpions were Abjured and chased out with relatively little fuss despite their "taint", but the Blood Spirits couldn't be allowed to walk away. I get that in a post-WoR Kerensky Cluster, arming your civvies was a no-no, but this was just an excuse to the Adders (who, as was pointed out earlier, did the same thing on occasion) who were simply waiting for an excuse to finish the job.
If only the Adders had gotten over themselves and revealed to the Spirits that they were right the entire time that they were saying that the taint of the Burrocks lived on within the Star Adders. Imagine what could've been had the Star Adders came to the Blood Spirits once the Burrocks proclaimed themselves a Clan again and said, "Hey, let's go bury the hatchet in these guys that you hate anyway!"
Sigh. Oh well, at least it's easier for me not to spend money on this brand now. Silver linings and all.