Rule update:
Minimum of 5 new topics (that's only one or two a week) in the bitcoin discussion board (make them interesting and relevant to news and continually reply to the discussion in the thread!)
What is the point in this and how is it even enforceable? Are you going to go through everybody's posts (potentially hundreds) one by one to check if they've made the mandatory minimum five threads? You can't even tell if they created the thread just by looking at their post history anyway. Seems more hassle than it's worth and will only cause problems for everyone.
Enforcing this should be pretty simple.
You have a stat panel for each person's profile.
You can pull out details - including post count and number of topics started. A simple script can do this.
Run this script at the start and end of the term - voila, you have the number of topics started.
In my personal opinion, this rule will lead to more irritating spam. If spammy posts are buried deep inside, you can ignore them. If there are spammy topics, they will be more irritating.