No it's to make sure donors know that the money they give will have a legal obligation to be used to achieve the mission statement of the organization.

No, this is to make the transition from a one-man show into a sustainable organization.

The organization bits came with >1000 issues, needing more committers. Now there are 8 committers and 1200 issues. And probably a dev list to handle internal issues.

I don't see the need for a financial organization, other than my arguments. Sustainability is much better without another entity interfering.

Yes. That is clearly exactly what is going on here. It's all about money. That's why the blog post explicitly talked about how focusing on money is a mistake.