Unfortunately that's not usually a good enough motivation for most companies. To be clear, I'm not arguing that I don't think it would be a good thing for them to release the code (I most certainly would welcome a fully open source rpi), I've just been confronted to this mindset a lot at work. Closed source is the default, releasing anything publicly means going through many hoops and levels of hierarchy. If there's no obvious benefit for the company and you don't have insiders strongly pushing for it it won't happen.

My bet — and IANAL — is that a corporate lawyer looks at the idea and sees no benefit, but an unknown, probably small, increase in potential liability. In that case why would they approve it? They're not evil, particularly, but they are analyzing the situation in terms of risk and benefit. Societal benefit doesn't make their list.

Also, the lawyer can skim-read the technical documentation, and even if they don't really understand it, they can reassure themselves that if there were any legal issues in it they would have noticed them. By contrast, few lawyers can read code, so they can't give themselves the same reassurance with respect to it.

> Societal benefit doesn't make their list.

Then I'm happy I'm not such a lawyer.