No academic benefit has EVER been demonstrated to have arisen out of "diversity." It is like picking a soccer team based on the first letter of their middle names - RATHER THAN picking the best available players (which is called "meritocracy").
What the Iowa legislature is wrestling with is the fact that while Universities pay homage to "diversity," they have disdain for actual intellectual diversity, and have become giant echo chambers where helpless Snowflakes spend 5 or 6 years learning politically correct nonsense, while never hearing an opposing point of view or learning to defend their ideas against an opponent using facts and logic.
But if history proves illuminating, any such law would simply result in aspiring academics LYING about their political views, in order to be hired. People who actually work for a living have little interest in teaching college.