However, somebody then gave me a link to what is apparently one of the main threads [0] in which they and Andrew Belt's main developer "got into it", and after reading that I was much less certain about who was behaving badly here (if anyone).
[0] https://community.vcvrack.com/t/do-open-source-plugins-need-...
Regarding the MiRack fork ... I am not certain, but I suspect that this author acted in specific ways that upset Andrew. I talk regularly to the developer of Cardinal (mentioned below), which is another fork of Rack, and thus far, things between them and Andrew have remained reasonably cordial.
Certainly as the developer of another open source audio project, if someone behaved the way the MiRack developer seems to have done [1], I would likely seek to exclude them from our community too.
[1] I stress the seems because it really is not entirely clear what took place.