You've misinterpreted the license. What it says is that the licensOR (not the licensEE) is a non-profit. That is, by publishing your original software under the NPOSL, you claim that you are a non-profit organisation. That's it.
Nowhere does the license say that you can't use the code outside non-profit orgs. In fact 17.d says very clearly that if you're not a non-profit, you are allowed to distribute your modified works, but under the original OSL license, not the NPOSL. So you can use, modify it and distribute it, only with a complication in the licensing.
The other amendment the NPOSL adds is where the original OSL gives a grant of patents and a warranty of provenance, and the NPOSL explicitly doesn't, because it's designed for non-profit companies, which have no money, so it's intended to reduce legal exposure.
It's a Free Software license in my opinion, and I bet you a drink that Stallman and the FSF would consider one too, even if they would not recommend using it.
Also note that the license's author is Laurence Rosen, who was General Counsel of the OSI, knows more about software licensing than most people, and who explains the details and rationale of the NPOSL in [1]
[1] https://rosenlaw.com/OSL3.0-explained.htm
If you have any other license that's OSI-certified and you think is non-free according to the principles of the FSF, I'm interested in learning about it.
One thing to take into account, though, is that the OSI is a certification body, and the FSF isn't.
Thhis means that the list of Open Source (according to the OSI) licenses is closed and published on their site. The FSF gives a set of principles and also publishes a list of licenses with some analysis, but the FSF's list is non-exhaustive, nor does it pretend to be. There are infinite potential free licenses that the FSF will not list, because its doesn't count license certification as one of its goals.