As an employee or contractor, you are paid for the work you have done.
No one owes anything beyond that, expected or promised.
A Company will release a contractor through a second party in a heartbeat for many reasons other than their performance.
And, while two wrongs don't make a right, other than the illusory position of control, why is this acceptable?
The contractor should have been more forthright in his target self-termination.
The work environment may have not been conducive of his ability to be totally honest on site.
The contractor should have notified his immediate contact point of his sudden change in plans.
Even if it was late night voice mail or e-mail as some Companies and Agencies utilize.