There are a lot of interesting oxymoronic concepts in Lilith's Brood. Throughout the series, the Oankali mention that the Human race is full of life and death, horror and beauty. Simultaneously, Lilith notices the subtle ways the Oankali treat the Humans. Their imprisonment isn't actively aggressive, but it's an aggressiveness hidden in kindness. "And they had done it all so softly, without brutality, and with patience and gentleness so corrosive..." (67). Also, when the ooloi and the humans are fighting, Lilith describes it as "gentle chaos."
Another trend I noticed is the fascination with pleasure and pain. The ooiloi definitely have an interest in both pleasure and pain, and Lilith, also, "perversely" enjoys the pain of aching muscles (146). When Nikanj induces "time together" between Lilith and Joseph, it is both a painful and pleasurable experience. "Now their delight in one another ignited and burned...They seemed to rush upward..." (162). This experience is soon followed by pain: "Her first solitary sensation was pain--as though she had been shouting, screaming" (162-163).
When it comes down to it, I guess there's just a fine line between all these things, which could be an extension of the moral ambiguity we've been having trouble understanding. How much of the Oankali's intentions are for the benefit of their race or ours? Is their philanthropy completely altruistic? We don't get to know what the Oankali really think, which is part of the problem. Either way, I'm still wishy washy on what I think. However, Nikanj's statement on page 153 really captured my attention: "We...do need you...In a very real way, you've captured us, and we can't escape."
The quote you bring up at the end of your post is particularly interesting. I think the Oankali lack both altruism and malice in their motives; these are potentially human motives and emotions, which may not entirely apply to the Oankali; they are somewhat out of place with the consensus-building of the Oankali, and the quote from p. 153 I find bears this out. It seems to me that the Oankali's motives for involving themselves genetically and otherwise with our race is a basic drive for them; they do it because they have a strong genetic imperative to continually adapt and change, one which expresses itself in societal modes that to us look like softened conquest, but for them may simply be the natural progression of things.