When these incidents happen, I really wonder how there can be any support for these radical types. You can rationalize/justify your opposition to Western policies or culture all you want, but blowing up Muslims at prayer just COMPLETELY negates your argument that you are fighting for an "Islamic" society.
Let's look at it from jihadi perspective. Anyone not of their thinking is murtad and kafir, and punishment for that is death. Period. No ifs and buts to their argument.
Since the upper dir population did not rise in favor of taliban, they deserve death. There is a also a lot of inner hatred and notions of "revenge" involved in their thinking, which is also un-islamic, as jihad cannot be fought for personal revenge.