Again, that's all bass ackwards. There's no barking to be done. There's zero imperative for the landlord to extend the tenants. It's only the opposite (when the tenant wishes to break a contract early as a result of a PCS order) where the service member relief act kicks in.
The scenario at hand is strictly an issue between the member and the DOD. The member got severely inconvenienced by the stop movement order. That's not on the landlord, nor does the landlord in this instance have any imperative to advocate on behalf of the member to the chain of command.
Life happens, but that's what happens when you rent houses. I always rented apartments in order to avoid the hassle associated with the volatility of house landlords AND the nomadic nature of military service. The tenants understand the military reality. Landlord's come home and needs his house back. Contracts fulfilled Period dot, pack your stuff and go to an extended stay. Or go rent another house for that short a time and roll the bones if apartment living is somehow beneath you. Go address your grievance with your chain of command, but leave the landlord out of it, he's no dog in this fight, and to portray him as an aggrieving party is complete BS.