Why not train them to do the function wrongly, see how long these non Americans last and how long the businesses can sustain using them. After all, what can they do to you, they fired you already.
Disney isn't that stupid.
One of the requirements to receive your severance bonus is that the employee you trained needs to be able to demonstrate that they learned how to properly do your job.
While I can't speak directly to what Disney is doing, it is not uncommon, when these kind of things happen, to tie an employee's severance package to having them properly train their replacement. Let's say, for example, you have been working for company X for 20 years and they are going to give you a severance package when you leave of 1 week's pay for every year you worked. Often times, in order to get that package, you have to sign a contract that states you will have to do "X" or not not do "Y" to qualify for the package, and if you don't sign the contract, you are not eligible to receive your severance.