Couple things, the Taliban was not considered a legitimate government, not by the US and not by the
UN:(from 1998)
"The United Nations Tuesday refused to recognize the Taliban as Afghanistan's legitimate government for the third time in as many years and kept the U.N. seat with the representative of ousted President Burhanuddin Rabbani."
So the Geneva convention would not be granted to them.
Also, even if they had been a legitimate government, if their soldiers do not abide by the rules of war, ie uniforms, then they are considered spies and all bets are off.
Either way, cremating the dead and insulting the enemy is not a violation of the Geneva convention.
You may want to actually read the GC.
I was suprised.
GE