One of the explicit goals of the NSF is to train the next generation of scientists. Part of that is making sure that you're creating a rich pipeline of people who are going to do innovative things. Broadening participation is much more about things like getting more (usually younger) people from all walks of life interested in joining your field. Which is basically an unmitigated good -- first, the obvious advantage that having more people who want to be in a field is good for it from the perspective of choosing the best folks. And second, the less obvious but perhaps more important thing that people with different perspectives often end up thinking about problems differently. It's not nearly as helpful to have 1000 people all focused on chasing the same problems with the same toolbox of solutions as it is to have 1000 people focused on different problems with different ideas of how to approach them.
I say this as a professor at a top computer science department. I have _never_ felt limited in my ability to collaborate with the best folks in my area. Ever. I do! And it's great! And I also believe strongly it's important to make sure we are growing those next generations of amazing people, because the thing that makes research awesome is working with them.
I would say this is exactly where you want that kind of policy. At the bottom, where you’re cultivating what will end up at the top. You want the diversity of ideas for exactly the reasons you stated.
People get upset as though this policy is dictating that a minority from the corner of the earth with no meaningful experience is going to be mandated into the role of heart surgeon or airplane pilot as well. That’s not how this works. However, those roles themselves stand to benefit from the diversified cultivation at the bottom of the stack, eventually.
Even very intelligent people seem to think inclusive policies mean that incompetent people will be promoted in private industry or government, but frankly, I never witnessed that to any abnormal degree until the people decrying it the most ended up in power. A game show host as president. A Fox News anchor as secretary of war. I can only keep a straight face because I’m so jaded by it.
Also, tickbox "I've considered this issue" questions which don't actually stop you from receiving grant funding with a team of middle aged, white male citizens from privileged educational backgrounds is not remotely the same as a clause enabling the administration to arbitrarily cancel your contract mid way through your project.
Especially not when said administration has a track record of cancelling things because they Ctrl-Fed outgroups they considered to be the enemy and discovered a completely irrelevant Latin prefix in someone's abstract.