No it's not.

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.