Considering that the Burrock Absorption essentially doubled the size of the Adders, as it was a suspiciously bloodless Trial, except for the Blood Spirit intervention/interference(depending on your perspective).
This isn't really the case. The Adders had 10 Galaxies pre-Absorption, and ended up with 11 Galaxies post-Absorption, so the most we can really say is that the Absorbed Burrocks merely replenished the rank and file. And it definitely wasn't suspiciously bloodless: on the Burrocks' capital of Albion alone, four Burrock Galaxies vigorously defended against the three attacking Adder Galaxies. After the surviving ranking Burrock officer prepared to Trial against Khan N'Buta,
then the Spirits jumped into the fray, and the rest is, well, history.
Very on brand for them…
I'm gonna disagree with that. The Spirits' interference in the Burrock Absorption was the culmination of a centuries-long feud and wasn't "on brand" for them at all, as they'd gone to great lengths
not to mix it up with the other Clans. The Spirits throwing themselves into the Viper Annihilation was an outlier and held no real purpose for them other than the writer wanting to chew them up before letting the Adders finish the job later.
Basicly, no matter how right it was for Blood Spirit to have interfered, the doom of the Blood Spirits was that decision, and the decision to not trade with the Cloud Cobras at Haven. If either of those two things had not happened, Blood Spirit might still be around.
That was the Lions, not the Cobras. The Lions' loremaster got her feelings hurt so she had her Watch steal the location of the colonies from the Spirits, exchanged that information with the Cobras, then came in with the Coyotes later to take what they wanted from the Spirits. The Cobras were the only Clan left that didn't try to prey on the Spirits, but dealt honorably with them.
The Spirits were
never going to survive, especially not after the Adders took the top-dog spot. Though some of their fans like to insinuate otherwise, the Adders were as deeply hateful of the Spirits as the Spirits were of them (you don't spend nearly three weeks straight orbitally bombarding the Spirits' homeworld and murdering tens of millions without a massive amount of hatred), and this was always going to happen. I mean, the Coyotes straight up betrayed the Clans entirely and helped facilitate a caste revolution against the warrior caste and the Adders more or less let them skate on that... but when it came time to punish the Spirits, the Adders went for overkill intentionally, not even making much of a pretense of carrying out an Absorption but straight up Annihilating them. That should tell one all they need to know.