I can't find a option to disable face morph for hair targets. 

I do not think you can. Same as cloth, the Hair is confirmed and would follow all head morphs (unless hair is an accessory, which is not in your case)
You may want to finish morphs and then re-rig the hair - weight painting it freshly (that is outside of CC for now until we blessed with CC3).

Thanks Ill do that. I hope that is fixed in CC3