What justification would also require wages to decrease?Actually it would be the withholding. The employee's withholding would have to be retained by the employer to achieve the 20% + price reduction...That means no 100% paychecks.
The justification is simple business logic and grade school math.
Where do you get that the employee's withholding has to be retained to obyain the price reduction???? The price reduction comes when the employer's embedded taxes that he pays on each unit disappears. When cost goes down, then price goes down. The tax raises the end cost of the product back where it was before.