There is literally no reason to do it like that other than incompetence. Platform migrations, especially for something as large as Twitter, are incredibly large undertakings that need a lot of skilled people. All those skilled people have long continued their careers at other companies.
You don't need to know how Twitter is run, that is simply IT and business management 102.
No, letting your contract run out before you have properly migrated is not a reasonable strategy, it's mind-boggingly stupid and pathetic.