No no no no. If it's really the case that Mojo has business assets that stbx would techninally be entitled to then that's that.... Yes, he quit on his kids. Yes, he left a higher paying job and bailed on his child support. But no reason to sink to his level.
Ethically, you are correct. But why is it that Mo has to fight both sides of it? Why is it not his problem? Tell me again... what's ethical about divorce?