To preface my comment, I’ve never been an active community member, nor have I been an active voice on this platform. Neither am I a good enough C++ developer to judge the quality of code contributions.
That said, I would take a more conservative stance here than others, and if Determine Systems intends to upstream (most of) their work, I think it would be very welcome in the project. As far is I understand, we are doing a lot of work with a small amount of people. We are after all, trying to change the world, by changing the way software is built. No easy feat.
I understand that this project being suddenly announced might come across as hostile or seen as a form of takeover to core contributors, however seen the way Eelco has been treated by the community as the initial “creator” of Nix, I don’t feel we should be quick to blame and point fingers. I personally also would be hesitant to communicate directly with the Nix community myself in that position.
In short, I think, we should focus on the good side, and not only the bad.