No, not crazy... sounds like she has a purpose. With full custody she can take them with her and live overseas.
It's crazy that she thinks she has a case. I think that even if she gets full custody, she can't get them passports without my signature, as their father. She'd have to have my parental rights terminated to do that without my consent.
Full custody would give her more legal leverage to use against me though, and she DEFINITELY would get much more support. She could also move away anywhere within the USA, and I'd have no say. I'd be relegated to writing a big check to her every month and seeing the kids a few times a year. THAT's my nightmare scenario.