Admins have the power to rebind your keys -- its a well known thing. They can rebind your entire setup if they want to. This is especially easy if they have adminmod installed. But the admin's have the power to lookup your IP address -- with that power, they can hunt your computer down.
I have admin control on my friends server and will look at the stat to kick/ban players and it does show your connected IP address. If an admin wanted to mess with you, he could get your IP, get to another machine and look on your box to see if you have shares on, etc -- WAY TOO EASY!
That admin probably rebound the keys to have mouse1 +kill, nothing big. If you want your keys to not be overwritten, make your config files READ-ONLY. The admins can't permanently mess with your box (they can also only mess with CS related files). If you think they messed with your box, exec your config.cfg and autoexec.cfg and your keys will be back. If there are any other questions to CS or HLDS, send them this way.
vash