Assuming it sets its own user-agent string, we can surely block that in mod_rewrite (if they tell us in advance what the user-agent string is)?
It seems apt to do this and make the recommendation that those who want to use this tool download old/cur and run them on their own machine (if changing the url is supported). We have more bandwidth than cpu after all. Likely speed up the tool severalfold as well resulting in a better use experience.
/brian