Meanwhile, Kayla just wants to be left in peace with her pills and her online boyfriend Wesley Crusher.
Wesley? No one likes Wesley (outside of sex pest Gene Roddenberry, as Wesley was his Mary Sue).
It's easy to assume that Kayla is being pressured into this by Nick or is just a passive observer to this garbage, but it could simply be a case of her being just as vindictive as Nick, she's just not online enough for people to actually see it. She can get petty revenge on Nick for trying to replace her with April by having him enact this stupid shit in public, taking the main brunt of the mockery for it, whilst she sits back and gets the victim treatment from a large swathe of Nicks critics.
People need to keep in mind that Kayla is as much a scorned lover as Nick is.
It's a great point. We just don't have any evidence of her being a particularly angry or vengeful person. (Sure, I'll accept incompetent, lazy, and a rather ridiculous human, but not hateful.)
I've poured over the (excellent) OP on Kayla. There are tons of clips. The most we've seen is her mocking Nick and being (arguably) passive aggressive as she told embarrassing stories about him.
We have some second hand reports on Kayla's ... maybe emotional make-up? ... that can be informative (if one believes the sources). We have the reports of Kayla getting cornered by Nick from two sources (the Toe with the baseball bat story, and "wet fart" Gabe with the "Kayla concussed herself to get away from Nick" story). The similarity between the two accounts paints a rough picture of Kayla and Nick's relationship. There's also Aaron's description of how the Rekietas would fight in other circumstances- Kayla berating Nick while he beats himself in the head, throwing books and other items, hysterical shouting matches. There is also Kayla enabling Nick's behavior of wanting April (by keeping Aaron distracted with her Gollum allure). We have the long history of swinging, per their own photos and anniversary show at Hedo 2, plus the YellowFlash corroboration now.
It's a fucked up situation all around, and I'm sure it's toxic as all hell. However, I don't see Kayla, in the present day, as wanting to reign hellfire on Aaron without Nick guiding her to that conclusion. Why?
You also have the paradox of "these people just want to be left alone", per Nick's account of their words. ("These people" being inferred to be Kayla and April.) Now Nick's a liar and a faggot, but contrast that statement to Nick continuing to seek vengeance on the Toe. As others have mentioned, a court case would 100% dredge up a lot of details we probably don't even know yet about the Qover. What would the win be? Maybe a hundred grand at best? Nick's a millionaire, per his own lying mouth.
Given what we know of Kayla, my inclination would be she would rather stick her head in a hole in the ground (well ok, stay in the bedroom and watch Star Trek) and forget about everything. I could see Nick getting her riled up at Aaron, but I just don't see Kayla having the stones to maintain the hate boner in the way Nick does. Her ire is focused on the Minnesota 2 she married. (He'd be a zero but for the trust fund.)
To be fair to Nick, a hate boner is the only type of erection he can maintain (without industrial grade pharmaceuticals or silicone ball torture devices).
Edit to add: some points of clarity