Yeah, normally I'd support making ONS that much more entertaining, but there are still two things to consider:
1. The strength/weakness of that vehicle, and how most players will probably sit around and wait for it to spawn so they can drive it.
2. [MiA]Warfare is only a demo server, and to host a mutator that large would require it to be a full version server (since, if I remember correctly, "adding things that are 'already included' in the demo version is okay, but UT2004 doesn't like adding new content in demo servers").