If GitHub had wanted a GitHub specific URL shortener and did not want to further perpetuate confusion about the relationship between git and GitHub, they could have gone with gh.io, ghub.io, hub.io, or any other domain name that isn't 'git.io'. 'git.io' sounds like it would probably be an official domain of 'git'. But, 'git.io' is (was) actually a URL shortener for a specific hosted service whose only relationship to 'git' is that GitHub uses the 'git' software for version control. GitHub is not maintained by the git team nor is it a project of the git team. Git can be (and is widely) used outside of GitHub.

GP is not complaining about a GitHub specific url shortener.