Walter did a vote for fast zombies, it won like 19-2 so he asked people to switch class. After a couple of rounds it seemed mostly everyone did except 2 people, him and this guy named billymayes.
Imo fast zombies ruin the "fun" of that map and if an admin spends SEVERAL rounds asking people to switch based of the majority want of the server, then I am glad he kicks people who don't listen.
If walter is "abusing" his admin rights by making the server/map more fun and balanced for everyone except for 1-2 people then perhaps there needs to be a new rule added to the "server rules list"