https://github.com/aws/aws-node-termination-handler/tree/e0260bd31fc6267fb04b32a0adf920983c436644/config/helm/aws-node-termination-handler has the following:

But looking at the code, the default is actually -1:
|
podTerminationGracePeriodDefault = -1 |
I think the confusion stems from the fact that Kubernetes' default is 30, so transitively NTH's default is 30. But if your pod has a custom value, NTH will not override that by default. This could be made clearer in the docs.