Right now (afaik) only the spawn chunk is protected from expulsion pylons, would it be possible to add a chunk radius config option for preventing expulsion pylons from being placed?

Currently it prevents it from working anywhere in the spawn radius. So 16 blocks away from the world spawn by default, but configurable with /gamerule spawnRadius.

well increasing spawn radius increases all protections, sometimes you just want it so people cant claim within 10 chunks of spawn but they can still get wood etc.

Added in 2.0.2.