From the screenshot, it appears they're running npm in a docker container inside the EC2 instance. It's curious that they did not use Container Sevice. I would have expected node to be running directly on the VM.
We should look at ECS though. Are you more likely to deploy if something is in ECS than if it's a straight AMI?
Though I must admit (1) I am not one of your customers, and (2) our BAA with Amazon prevents us from using ECS. We typically run node on ebs backed m3.medium instances running Amazon Linux.