I think the point of that WCAG statement is that you shouldn't use title and access hide when the text would benefit everyone not just some one using a screen reader or just a sighted person.
The point of the mentioned ticket is that a user doesn't understand what Tim Hunt stated that the user's name when linked in Moodle always goes to their profile.
So to Tim's point Moodle is not like Github. A linked user's name doesn't always go to their profile. It can go to many different places based on where it is. Whether the user's name is at the site level, or the course level. Whether the user viewing the name is a teacher viewing a student's name or a student viewing their own name in an activity.
The reason for the ticket is that to be accessible links need to clearly tell the user where they will be going within the system if they click the link. Clicking Bob Smith in an interface doesn't really tell you that you will go to Bob Smith's profile. I would even argue that Github's use in not WCAG 2 compliant. Just because a well known product does something doesn't mean it is a good example of accessibility. It could be a good use or it could just be they haven't been sued over it. Educational institutions have legal requirements to be accessible that makes their accessibility compliance far greater than a company like Github.
Take bootstrap for example. It is used all over the web and has well known accessibility issues that Twitter has acknowledge as currently existing and having no resolution for.