It's only for some maps. Most regulars know which maps fast are just ridiculous on, and which don't matter.

Also, it's the admin's job to keep the server in order. If half the server or even a few people say that fast zombies are lame and shouldn't be used on "some" escape maps, then the admin can tell everybody to not use a fast zombie and to change their class. If you don't listen, then suffer the consequences.

Sometimes i'll use a fast zombie on jurassicpark, but i won't tag anyone. I usually only do it to rush to the end and close the gate on the humans. I won't usually tag anyone unless they repeatedly shoot me, KNOWING I WON'T TAG THEM.

So basically, if an admin tells everyone to get off the fast zombie class on a certain map, then just do it. Don't try to rebel, and you won't get abused.