Yes. :) Well, the source code was actually supposed to be released under the BSD-3 license even back in 2016, after the game was abandoned in its commercial form in late 2014. But the plans fell through and when the official community site (with discussion forums, wiki as well as sharing levels for the game) then shut down in 2018 without a word from the original author, it was assumed that the open source release would never happen anymore.
I had played the game when it originally released in 2013 (and I had also played the prequel from 2011), so my time with the game goes back for a long time. When I came back to the game after a year or two of inactivity in late 2019 I discovered the sorry state that the game was in, and decided to begin reverse engineering the game to create a new unofficial community site for it (I have a longer blog post that goes over it in some more detail, up to and including after the source release). During this time, the original author was more or less impossible to get into contact with, but one day in August of 2022 he just stumbled into the unofficial Discord server we had for the game and got to see the stuff I had done. He was very happy to see what I had accomplished to try to revive the game on my own, and after he had reintroduced himself to what remained of the community and we had talked for a while, the topic of releasing the source code was brought up. Which of course he was very enthusiastic about.
In the end I didn't end up actually being the one who published the source code to the Internet and such, but I was definitively the one who got the ball rolling again and at least I got to be the first one to build it natively for Linux, among other things. And when the original author had to leave again for personal reasons I was given the maintainer hat in his absence to keep the open source project running in the hands of the community. Apart from the fact that there did not end up being a lot of momentum for the development of the game afterwards (whether it be due to the release happening so many years late that people moved on, the unfortunate state that the game's source code ended up being in, or personal incompetence on my part), Principia has probably been among the best success stories of an abandoned commercial game in modern times being open sourced and officially picked up by the community, and it also likely had the best circumstances to make it happen.