Do you assume that because Karimov boils people alive (an evil thing to do - but by HT theory - an "action", not a "law" and thus a "thulm") that he is illegitimate by that fact alone? Isn't that Thulm and oppression which your own books say must be disobeyed but cannot of themselves justify rebellion?
Why was it Haram to rebel against Hajjaj bin Yusuf who killed a Sahabi, and yet Halal to rebel against Karimov when he kills Muslims? Surely you need "Qati'i Kufr Buwaha?" So please show me where that is, not where Thulm is, we all know there is Thulm.
The only thing you can say is "because karimov rules by Kufr and Hajjaj didn't"....well then, please show me where the Qati'i Kufr buwaha (not thulm)is in ALL rulers (inc. Karimov) so that you can establish by Qati'i evidences that there is no Islamic state any where in the entire world.