"Securing government comms" can be misleading. Tor is not by itself a secure channel, but may be part of a secure channel if you're concerned that a local or semi-local adversary may intercept your communications. My understanding is that Tor was developed primarily to facilitate informants and dissidents in countries with restrictive internet access policies, like China, who would not take kindly to seeing communications between Chinese IPs and U.S. military IPs.

There is a very widespread and dangerous misconception that Tor is a one-stop shop for secure or anonymous communication. This is not true. You need to encrypt your messages separately. When outside the onion network, Tor actually exposes all content sent through it to a third-party, the exit node. This means using Tor may be more dangerous than not using Tor if you don't know what you're doing.