Thinking on that, I feel as though the Spirits feared the Adders were going to come sooner or later. The Absorption War brought the Spirits front and center on the Adder dartboard, but if the near entirety of the Burrock Touman was Absorbed I'm not sure much would have changed in the preexisting Burrock-Spirit feud, just with the former-Burrocks having far stronger backing and support than they previously did. The Spirits, fierce Warriors but isolated politically and concentrated mainly on York, would have made a fine whetstone to sharpen the swollen Adder Touman and help integrate it.
Damned-if-they-did, damned-if-they-didn't, I think.
I disagree, at least in part.
Without the Spirits' interference, the Burrock Absorption would've been
much bloodier for the Burrocks and Adders alike, as the lion's share of the losses in that conflict were due to the Spirits jumping in (per the Adder entry FM:CC and WoK). Without them showing up, the Burrocks would've had no reason to team up with the Adders and would've been much more likely to fight for their right to exist.
I'm 50/50 at best on the Adders still going after the Spirits without the Spirits' interference in the Absorption. It's true that one of the reasons for the Adders going after them was to mollify the Burrocks in their ranks, but the primary reason they did so was to punish the Spirits for their interference (and to avenge their losses, which were considerable... remember, the Spirits took out three of their Galaxies and four of the Burrocks' Galaxies for the five they lost).
The Adders might've decided to do that touman sharpening on other enemies of their Clan, or the invading Clans, and seized power in the Homeworlds much earlier, without having to get in bed with Brett Andrews. On the flip side of the coin, the Adders might've had a much worse problem on its hands with the Burrocks in their ranks, as their increased numbers in the touman and in the lower castes could've magnified their discontent in the tight-knit Adder ranks.
