Page access rights of deleted users are not displayed although they are effective

The page access rights of a deleted user are not displayed and, hence, cannot be removed, but continue to influence the access rights of other users. So, either these rights should be displayed or they should be ignored by the rights system.

My case: I once created a guest account and made a page explicitly visible to this user and other users. Later I made up my mind and removed the guest account. Recently, I wondered why I gave explicit view rights to this page and removed it for all users and groups displayed on the page administration page. Afterwards the page was no longer visible to the users. I had to use a XAR-dump of the page to reveal the hidden dependency on the guest account, had to re-create the guest account, remove the rights of the guest and delete the guest account again.