Spawn protection going to ruin quite a lot of maps for normal players (already discussed).
Banning "worst offenders" (even temporarily) is out of the question (cuz small playerbase and ppl generally disliking when they are forced to play certain way).
Autokill on paper sounds ok, if there is a way to differentiate just lame spawnkilling from runner's kill streak on attack/exit. But I think it will render some small maps even more unplayable when server is packed (crates, bolt, etc).
So,,,crazy idea: how about community get their shit together and use vote to kick people who only spawncamp (like that lamer ez or w/e it calls itself)? Like don't wait for some savior to come and solve your problems - use tools that are available to you to solve them yourself.