This might be a Stupid Question but what old Grudges do the Crab/Scorpion have with each other?
Assuming that the Evil Spirit Theory is real and works by inflaming resentment and grudges and that the EST won't try the same tactic twice that would mean that the Scorpion would be next in breaking alliances via manipulating old grudges.
Plus there is the chance that Maturu might be vulnerable if he is actually the one Sosuke punched during his backstory.
Would really suck if another one of his Friends turned on him for various evil supernatural reasons.
The thing about Crab/Crane relations, well, they're long, complex, and full of history, but..... At their essence, it's a clash of values.
Direct Duty, vs Elegance in all things.
When it comes to the Scorpion, it
really isn't the same. Indirect Duty, Vs Direct Duty.
Note, there are many points of conflict, where one or another have had run ins, but...... When Standard Crab runs into a problem, a "Do I do Duty or Honor?" he has the same answer to Standard Scorpion. Different styles, sure, but still. Duty uber alles.
Standard Crane goes "Duty, Honor? I die Stylish!", and either chooses one or the other, or tries both. While looking Awsome. Unless their Daidoji, in which case, they are very Standard Crab.
All of which is an expansive way of saying, Crab/Scorpion fight's going to be harder to start.