I can see why it's not a priority to fix but perhaps there could be a hierarchy of relationship types? E.g. if you correspond with someone directly then that's how your relationship with them gets stored, superceeding any realm relationship with them, etc. That why removing all contacts of a realm relationship type wouldn't remove people who have been corresponded with directly?
That...might be a much quicker fix.
Could you please file a bug report with this, so it doesn't get lost?
