soldiers sailors act on a lease option

One of my lease option tenant/buyers informed me today that he will be moving to Korea in 3 weeks per his Army orders and referenced the soldiers sailors act as a way to break his lease.

I understand that I must let him out of the lease without penalty but need to know what about the lease option fee?

The lease specifically says that this amount is non refundable and can only be used as a credit toward the purchase of the home.

Thanks in advance for the input!