Yikes. My first comment is that this is a mess. They need an accountant to unravel all these errors.
First, the administrator should not have accepted the excess contributions unless provided by the plan document. This could be a disqualification issue depending on the plan provisions.
Second, the administrator should have returned the contributions directly to the executive. The company should not have returned them. I am afraid they could be construed as an additional payroll payment to the executive
Third, the administrator could have kept the excess contributions, but the executive could not have deducted them and instead paid the appropriate taxes. Of course, the plan would have to permit excess contributions.
Fourth, I am not sure that the earnings should be returned to the company. I believe they belong to the assets of the plan and should be distributed among plan assets. I can also see an argument that the earnings on the excess contributions should be distributed to the executive, but taxes withheld.
There are errors due to actions by the executive, company, and administrator and I don't have the answer as to who gets what when unwinding this mess. The main goal is to be sure that all participants are not hurt.
At this point I will revise my advice to they need an accountant AND attorney to unwind this mess.