If GitHub were the sole game in town, maybe (probably) they wouldn’t have switched. But it isn’t, and they found something which in their view is an acceptable replacement and less worse. So yeah, maybe they don’t ethically agree with everyone on every thing up the chain, but they apparently agree with them more. That matters. You take a stand where you are able to.
You are making an ethical judgment when you say, in essence, that 'it is wrong for businesses (and non-profits) to attempt to act in an ethical manner, aligned with their mission statement'.
Making an ethical argument about the purposelessness and futility of ethics is... interesting to say the least. Please, consider stopping the internet today and instead spend time with a book on ethics that you think agrees with you sensibilities, and then look at this situation again.
People that use the former like a slur seem to need to believe that the latter cannot be true.
I wouldn't want to live in a world like that personally, assuming nefarious intention behind every good act (people in positions of highest power excepted). It seems exhausting.
Andrew Kelley means what he says and says what he means (in an on-the-spectrum way). It makes him off-putting and charming in equal measure, depending on the issue. But you shouldn't assume that this is a mere 'signal', it is what he believes.
Speaking for myself, I do disassociate myself from unethical products and people. It's not always as soon as I'd like, Amazon being a good example. I've never regretted doing so.
It's not even worth bragging about, who would even care? I just despise lying, and if I want to believe that I behave ethically without lying to myself, this is the natural consequence.
They are not going Categorical imperative here.