H1-B becomes invalid if the company fires you. It would have been worse if he'd already got here, but knowing how much effort goes into moving countries (particularly to the US), that is a very small consolation.
Some consolation, in that case, according to Wikipedia: "if the employer should dismiss the employee, the company is liable for any reasonable costs associated with relocation back to the employee's last foreign residence"
Reasonable costs here appears to mean "a plane ticket home", and appears to only apply if the former employee elects to return home; in particular, the first page of Google results will tell you that the company isn't responsible for moving the former employee's property (which is the real relo expense).
