When in folder view(placed in panel) location is set to Desktop(desktop:/), clicking on a *.desktop file with Type=Link should change to the pointed directory (this is what FolderView tries to do).
Now in this context FolderModel::isDir, as expected, returns true but since FolderModel::cd uses KFileItem::isDir, it evaluates to false and directory is not changed.
So using IsDirRole in place of KFileItem::isDir can resolve this conflict.

Before Applying patch:
Set location to 'desktop:/'
Clicked on 'Home'
Nothing happened (neither cd nor dolphin opened)

After patch:
Set location to desktop:/
Clicked on Home
Directory changed in place and contents of home directory shown.