I do realize the exact timing, Eich was CTO when he made the donations, was proposed to the CEO role when this was already known, accepted the nomination, one board member resigned in protest and then it all blew up and Eich resigned from Mozilla entirely 11 days later. Clearly, he did not make the donations in those 11 days.

I could have worded that comment a lot better but the intention seems pretty clear to me: Your actions as a CEO (even past actions) are going to be viewed in a different light than your actions as just another employee, even a co-founder, and what wasn't a problem before the CEO nomination quickly became a real problem, both for Mozilla the progressive entity as well as for Eich himself. Whether the donations were made several years, months or weeks before his tenure as CEO are not important.

The one thing I did get completely wrong - and which I will also acknowledge - is that I thought Eich could have legally made those donations anonymously (it was argued quite strongly during that time that this should be a possibility). I did not realize that this was illegal.

Your original comment is right there for everyone to read. In effect, what you've managed to argue here is first that the sequence of events is very important (your whole argument being that Eich "as the CEO" should have made his donation anonymously), and then, when called on that, that the sequence of events matters not at all.

Sometimes the best response to a rebuttal is just "TIL".

We're supposed to assume good faith, right? What he said he meant sounds plausible if I do.

This is a case of a commenter not knowing the sequence of events, realizing their mistake, and then pretending they were right all along.

Good faith doesn't mean "be very afraid to criticize others when they lie".