Terraform is I/O bound on cloud provisioning APIs (its CPU performance doesn't matter), and its complex object models need to be extensible. Python would have been a better choice.
As a former maintainer of Terraform, I 100% assure you that Python would have in no way been a better choice.
While Terraform is I/O bound to some degree, it has a large degree of concurrency - something quite miserable to do in Python.
Terraform does not take full advantage of even the type system available in Go, but a dynamic language would make things even worse. I do not think Go is the ideal language for programs like Terraform, but having spent many thousands of hours in that codebase now, the answer is stronger types (likely Rust), not fewer.