I honestly think in activeness is an issue but a couple weeks in activeness shouldn't be a reason to be kicked, maybe 2 months without a sign of life if s/he didn't state ahead that they will be inactive since we never know the other person's personal problems.
What i wanna say is, i think 2 months should be the max amount allowed for a person to become active again, and also you should specify what active means since its quite a global meaning and some people can find a loophole to that.