The article mentions that port 22 was nice because ssh is a cross between ftp (port 21) and telnet (port 23). Why did they take those ports and 22 was left empty in between?
A good example where HN comments are useful. The TCP predecessor NCP used odd ports for “incoming” data, so the even port 22 was still free.
Also regarding the SSH trademark, see this https://www.openssh.com/ssh-dispute/ for history (2001)
Just to augment this article: https://www.openssh.com/history.html