SSH keys don't really have any interesting properties (like name or URL), but you could maybe do something like this:

$handle->setName(pht('SSH Key %d', $key->getID()));

For example, I think that will make bin/remove destroy render things a little more cleanly. As-is, it will render something like this:

...
This object will be destroyed forever:

    - PHID-AKEY-irxjvgxviobklieu2677 (PhabricatorAuthSSHKey) Unknown Object (SSH Key)

    Are you absolutely certain you want to destroy this object? [y/N]

...but if you use setName() it should render something a little nicer, more like this:

This object will be destroyed forever:

    - PHID-AKEY-irxjvgxviobklieu2677 (PhabricatorAuthSSHKey) SSH Key 234

    Are you absolutely certain you want to destroy this object? [y/N]

Stray debugging print.

You don't need to do this, since we're only deleting the object itself (SSH Keys don't have any sub-objects or sub-rows, like Owners do), and the $this->delete() call on line 112 will take care of deleting the object.

So the body should be fine as just this:

$this->openTransaction();
  $this->delete();
$this->saveTransaction();