So are you defending the Afghanistan Taliban?
Jesus wept.
Your line of argument is like this:
b-"Al-Qaeda enslaved lots of Yezidis"
a- That was ISIS not al-Qaeda
b- "Are you defending al-Qaeda?"
; is ... not a terrorist group?
While there is certainly a fair dose of political expediency in the way it is used in the OP, in general you would expect the US government to have a more nuanced approach than simply viewing everyone as identikit 'terrorists'.
It is hard to deny that armed insurgent is a more accurate description of the Taliban than simply terrorist. Same is true for other groups such as ISIS and Boko Haram, who have armies and seek to take and hold areas of land rather than simply carrying out individual attacks.
People have a problem with them not being called terrorists because it terrorist has just become a synonym for 'bad guys who hate America' and armed insurgent doesn't have the same emotional punch. If you call them armed insurgents then it seems to some people as if you are giving them a ringing endorsement and absolving them of any crimes, rather than simply describing what they actually are.
The problem is today the only important thing for politicians is which particular carefully crafted 5 second soundbite they play on TV, rather than any attempt at keeping people informed accurately. The public is often so misinformed that many issues exist in a 'alternative reality', where politicians create imaginary solutions for problems as they exist in voters' heads, rather than how they exist in the 'real world'.
'Terrorism' is one of these key areas which tends to exist in a magical fantasy land with very little grounding in what is actually true.