Yeah, this was sort of a concept map, and I can see that I didn't pull it off. I may take another crack at it, applying the lessons learned here. I still think it could be an interesting way to play the game. I just need to make a better map for that purpose.
Actually, it is not a viable idea. Firstly there is the problem with no-one being able to post an inversely better score since the web site only records the shortest score as the best score. So it is a one-shot deal.
Then, as you have already seen, unless you continuously jack up the emitter strength, either everybody gets overrun by creeper at more or less the same time, or one can get to a stable-steady-state position where you just let it run, hammering the creeper indefinitely. Then it is a matter of how long (how many days) you don't need your computer to do anything else.