@patware I don't know the details behind this exactly, but theoretically if a group wanted to take another down legally, it wouldn't be a civil suit (scanlation group v scanlation group), it would make much more sense for it to be a legal suit (scanlation group 1 informs relevant authority about scanlation group 2's identity and an outline of the laws broken, relevant authority prosecutes scanlation group 2).
Then there's the slightly meta lawsuit strategy of the one with more money drowning the other in legal action, even if they won't win in court they may be willing to go if it destroys the other financially.
Idk, i don't really like speculating on this stuff because of just how nuanced situations like this can get, I think it's good enough to stick to the facts as presented (someone in JB threatened legal action, Leviatan dropped the series because of it).