This is ridiculous. The standard isn’t “are they unbiased” because it is utterly unachievable. You know this and you cling to it anyway. What matters is whether

This is ridiculous. The standard isn’t “are they unbiased” because it is utterly unachievable. You know this and you cling to it anyway. What matters is whether their bias materially influenced their conclusions. They have provided analysis and data backing that analysis. It is now up to you as a skeptic to find fault in that. “They are biased” is lazy, intellectually dishonest, and utterly unconvincing. It is a canned response that can be given to literally every conclusion ever reached and so can (and has been) dismissed out of hand.