Firstly, You're comparing the Brits. with the Taliban.....
The Brits. were an armed forces with central command, these Talibs. are separate groups/factions who work according to their immediate agenda hence they cannot be held accountable for anything....they're savages and won't be moved by non-violence.....
Secondly, Gandhi's philosophy only sounds good on pen and paper, it's not practical......we would probably be under British control today had there been no World War............they gave up not due to Gandhi's philosophy but because of WW2.
Thirdly, they can call for U.N intervention and wait for them, in the mean time getting slaughtered.......but everyone wishes to live you know....and everyone has the right to protect themselves.....