There is a lot of misinformation and/or urban myth on this thread about Ford's ability to enter the US.
For amusement, I have looked into the US law on this subject in some depth.
His options are:
1. Try to enter and be admitted. This would require that he luck onto a border agent who knows nothing about his admission of cocaine use and misses the record of his voluntary withdrawal at Chicago. This scenario is very unlikely.
2. Try to enter, run into a border agent who sees the record of his voluntary withdrawal, and once again be offered the option of voluntary withdrawal. This scenario is very unlikely.
3. Try to enter, run into a border agent who sees the record of his voluntary withdrawal and be subjected to a hearing on his ability to enter. This scenario is very likely if he does not have a waiver, and it is very likely that he would lose at such a hearing, with the result that he would be deported.
4. Apply for a waiver. It is very likely that he would get one , especially (but not only) if he was still a public official with a potential need to attend an official event, when he applied, because he did not admit to repeated, continuing use of cocaine and his criminal record is limited to the DUI in Floriida that caused no injury.