I think they posters in that discussion mean that they want to check the canEdit permission in /cms/code/controllers/CMSMain.php SiteTreeHints() (so part of Silverstripe's CMS core).
It seems that the code that handles this is checking canCreate, but not canEdit. So these devs are talking that doing so would resolve the situation.
It also seems that no one has touched this one for quite some time. You could comment on Github to see if there's an update. They were talking about doing it another way, so someone there may know more.