Digging into the code a bit I see it just is starting a subprocess which makes sense now why it is terminating on the sigterm/ctrl+c (signal it sent to whole process tree) https://github.com/pulumi/pulumi/blob/master/sdk/python/lib/pulumi/automation/_cmd.py#L55 It seems like this could be enhanced to deal with a cancelation/async run that way it can be gracefully stopped rather than abruptly terminated.

It would be great if you could open an issue with these suggestions via github.com/pulumi/pulumi/issues/new

logged the issue here https://github.com/pulumi/pulumi/issues/9103