I definitely agree that we need to think about people, that was a large component of "you can't swing resources around freely". Firing people is not something that I would like to see. The point I was trying to emphasize is that it isn't as if Mozilla just happened to have X people with design skills and Y people with whatever other skills. There was planning to build the teams and planning to pick the projects. So while I agree that you can't just put people on random projects I wanted to point out that Mozilla had a lot of agency in the decisions that lead up to a team working on the redesign, it didn't happen just because they happened to have a bunch of designers available.
I don't think it's considered rude, since "Human Resources" is a widely accepted term.
Human resources is less bad because it doesn't refer to specific people. And most people can't choose what the department is called. But they can choose what they call other people.