They have a single client running a single 10 sec job in a day?
They plan to continue having a single client running a single 10 sec job in a day?  The workload does have to be spiky to make the cloud cost-effective. There are workloads which are not appropriate for AWS. For any serious client AWS is a bad idea simply because there is single tenant (Netflix) consuming such a high percentage of resource that if they make a mistake causing a 40-50% increase in their load everyone gets f#$%ed.