An obvious first question is whether the existence of suffering-hating civilizations on balance increases s-risk (mostly by introducing game-theoretic incentives) or decreases s-risk (by exerting their influence to prevent suffering, esp. via acausal trade). If the former, then x-risk and s-risk reduction may end up being aligned.

Did you mean to say, "if the latter" (such that x-risk and s-risk reduction are aligned when suffering-hating civilizations decrease s-risk), rather than "if the former"?