That will physically force the UPS to change to UPS Ground regardless of what they pick when the Discount Coupon has Free Shipping set ...

They can change it to a higher method as many times as they want to, but it will keep reverting to UPS Ground when that Discount Coupon is set with the Free Shipping ...

If they don't like it, they can remove the Discount Coupon by entering: remove and take the shipping that they want ...

If they try to re-add the Discount Coupon, it will again switch it to UPS Ground ...