yeah my first question about an assumption you are making is how would I know that this user is suspicious? Maybe you know this because of the intimacy you have with the community etc but if this user joined Relume, I don't have enough information here to make any decision or take any action. I would have to wait for a negative action from this user and react to that.
I do like Andrew's suggestions for then automating some of the monitoring of that behavior and taking action on my behalf, alerting me, and then letting me review said actions.