Finally, here's a more useful answer from James Bottomley: https://lore.kernel.org/all/Zxpqnf1M8rPTB4DN@black.fi.intel.com/T/#m99bf59e0a5930460de743daaf31192cf1c8b9e96
The situation still looks odd when you consider that:
1. NetUP is not on the SDN list;
2. Neither is MSU;
3. None of the maintainers have personal sanctions against them;
4. While it is possible that they confused public mail.ru addresses with corporate ones, this wouldn't explain why they removed a maintainer with a personal mail server, so it still looks like a blanket ban.