I think simply if a muster reply via email/forum or contact with ones commander when asked where their whereabouts are should be enough. As it stands right now someone has to comply to this rule for being considered active via the forums and a muster reply doesn't count:
Any officer that consistently places four informative or entertaining posts a month (i.e. one per week) will be considered an ‘active’ officer.
Who decides what informative and entertaining is?? Also note it has to be done consistently.
Also there are really only 3 out of 5 for your average member to be considered active. Maintains our Club, or Army, Webpages, Designing New Napoleonic Game Titles and Playtesting New Napoleonic Game Titles is for a very privileged class of people. About 3-5% of the membership qualifies for this from just a rough estimate in my head.
If you want to clean off the rolls, you need have a proper system to do so. Typically a good rule of thumb is allow for at least one year of no activity AND no contact with the person. The commanders should make every effort to follow up with the person. Commanders serve the members and these have been some of the duties performed by them over the years. You can even delegate a clerk or someone who's task is to do that. The CSA in the AWCGC did that for a while.
While we are on the issue of Commanders, when I define commanders I mean from Cabinet all the way down to Brigade Commander. The leadership has to actively engage the members and on a routine basis. It shouldn't be assumed or expected that members are paying attention all the time. We all have real lives to deal with. If you don't routine engage your membership via direct email, all the forum posts, congratulations, chatter and sabre cry is useless at a certain level. Leaders have to lead. A successful army is one that the leadership engages the members on a routine basis. I know if Bill Peters was here (and I am sure he is reading this, "Hi Bill. Hope you are well!"

) he would argue till he turns blue in the face that you have to regularly contact your men, even just to say hi hope all is well. If you're just some name that mass emails them once a year or so, you are not a recognized entity possibly. You have to establish relationships with your men and the members of the Club. When you establish good relationships than the potential for positive replies goes up.
Why do you think I always did custom emails on top of forum announcements?? Because it was direct to the officer who received the honor, it praises them, it recognizes them directly, it shows you know who they are, it is personal for them and for you, it might garner a good response, it shows we respect and value the time of our members. Every time you thank the officers under your command, personally and directly, they gain a better feeling of being a part of something. They may not let you know it, but quite a few do. But you have to build that relationship.
Another example. I do a lot of work for the Colonial Campaigns Club (CCC) our sister Club. Last year I assumed a lot of new duties on top of what I already had. I started actively engaging the membership in semi-routine emails, updates, Newsletters et al, Club wide. I had approval from the other commanders to do so. Folks hadn't heard much for sometimes years from much of anyone. Well what were the results, people who knew me already started to engage with me, after couple of times of doing it folks who were dormant started to engage too, telling me about them, asking what was the latest, stuff like that. We also did/still are running a open format tournament to get the members involved, it has gone generally well. Members who were quiet for years started to come back and engage with the leaders and other members. We thanked them for it, for their time, kept things positive and encouraging and got really good results. I have been preoccupied a bit lately, things have slowed up a bit, but each month I gather up all the names on the list of those who have played games and I thank them all by name in an email. People do appreciate it.
Also people appreciate when you are sympathetic to their hard times. Even as a stranger, it is nice for people to hear. Someone is long term ill, issues at home, having issues with money or the stress of a job, what have you. They are going to get a bad image if you just say oh well and kick them form the rolls. But if you are sympathetic to them, willing to understand and say, "Hey I know what you mean, we'll be here when you are doing better. If you can, when I check in on you, just answer back and let me know and all will be fine." That goes a long way and it shows you respect them and value their time.
So I guess the point is you have to give a little to get a little. You can't just expect the membership to just come and fall into line. You have to truly engage them on a meaningful level and build a relationship with them.

I think that is far more important than any rules that can be made.