It seems like his main point is that a law shouldn't be allowed to dictate whether a political party is disbanded. Which is 100% correct in any modern democracy. Low activity means the party is inactive. It's not the government's place to say that the party is
dissolved because of that inactivity though.
A political party can be inactive but still exist: indeed though, its subforum shouldn't necessarily be kept live in that event. The party can exist without a subforum. Unless I'm mistaken, you're saying that you want to know what we should do about inactive political party subforums. Subforums should be archived if a quantifiable activity quota isn't meant.