I agree that it would be preferable to include a specific reference to territorial governments. It may be necessary to refer to Nunavut differently from the other two territorial governments, even though that would require further thought. As you highlight, it arises as a public government in response to a modern treaty, and has a bit of a different relationship to the country than the other two territories. It is ultimately public government. Territorial governments are not listed or enumerated in the act, and they should be.
On February 20th, 2019. See this statement in context.