FWIW, having it spelled out in the Plan Doc would be best, but I would not have a problem calling this "extra vacation pay" earned on the day before termination, or something similar, if future terminating employees are offered the same deal, to avoid discrimination charges.
The employer may also wish to look into how it affects other benefits. For example, if the DOT is out 2 weeks (with the employee not required to show up during those 2 weeks), is the employment extended into the next month, and is the employer then required under ACA to offer medical coverage for another month? and like that.