Freeze his head only? If that is the extent of it, then there is no intention to bring him back to life - only to preserve DNA.
The human consciousness resides in the brain.
The people who only have their head frozen will have to have some sort of new body grown for them.
But the ability to safely unthaw a frozen head and give it a new body still remains in the future.
No; the intention of freezing the head is to build or grow a new body using the same future science that allows the frozen body to be revived and cured. If the intent was only to sell DNA, Williams' son could have frozen any old bit of flesh.