Mugabe probably is the most demonized politician/ruler in recent history.
Why are the Western Powers not taking him out? Considering they couldn't tolerate the 6 month period of peace, after a decade and half of violence, that was brought in by the Sharia Courts and they attacked Somalia and removed them from power.
Why don't we see a similar treatment for Mugabe, if he is so bad?
Because Mugabe is not a direct threat to America...pretty simple to understand really.