Our admins are not immune to kicks by normal players.
But they should be.
The playersvotes plugins does not block the "callvote kick".
I have replaced the playersvotes plugin with two other plugins:
votekick and votemanager2
Votekick offers the "votekick" command and votemanager should block votes against admins.
Little testing here on my local server with my notebook and PC showed the expected result.
But more testing needs to be done on our real servers.
Currently only alServ2016 (connect 85.214.222.39:27016) is using the new combination of votekick and votemanager2.
After successful testing it should be deployed to all servers.
It should also work for L4D.
But I have not tested it so far.