Feature request Select/purge users who are logged in, but idle

My group has a policy that you have to actually participate to avoid being removed. I'd like to purge people who have not *posted* in some amount of time. (~3 months, 6 months, something like that). However, the only way the app lets me purge people is those who have not logged in for some period of time (7 or 30 days). That doesn't help me with people who have logged in but not said anything in months.

Feature request: A way to get a list of users who have not participated (posted or signed into a voice channel) in X months.  Like Purge now, ideally I'd be able to then kick them en masse, or whitelist a few to not kick (if I know of extenuating circumstances) and then kick the rest.