If scientific investigation shows that there are many causes that have a relevant impact on "A", then saying that "A has multiple relevant and possible causes" is not hand-waving. It's stating the fact.
Hand-waving is to pearl clutchlingly throw out vague terms like "affirmative action" and "diversity statements" without properly stating what the mechanism is supposed to be and without providing any evidence that it is relevant in the last.
You know, polemic tribal whistle-blowing like you are doing. That's hand-waving.
And this is circling the wagons. Sorry but I can't believe someone who is intellectually honest is capable of writing such thing. You are either blatantly ignorant on this matter (and shouldn't be talking about it at all) or taking me for a ride.
It's preposterous that I have to explain how requiring a document in which you state allegiance to leftist ideals has an impact on the political makeup of admissions. I don't have enough frontal lobe damage to take you seriously.
What you show is that there are not many conservatives in academia. The reason for that is manifold. It could be that they are forced out. It could be that their views are changed with higher learning and turn progressive. It could be that conservatives self-select to not go into academia.
Pointing that out is not hand-waving.