yes this is perfectly legal to do, but as a human you can not ztele away from a zombie. zombies are allowed to use !ztele as an escape if being held back by gunfire.

I'm thinking the zombie spawned and wasn't doing anything, so people decided to go zombie hunt it. turns out he was just afk for a bit and came back to see him being blasted by you or a number of people. you just got unlucky that you were also standing near a spawn point.

you wanna know how to fix this, stop being a noob and learn to kill zombies faster. unloading a gun is not the way to go but you wanna pull out your pistol and shoot it in the head constantly insuring all head shots for more damage.