Granted, ccTLDs has been already going on for years before USSR change their pronoun to were. Mostly for email, no idea if ccTLDs found their use on BBS.
I can understand .su continuing because Russia pretty much took over everything that represent Soviet Union elsewhere (embassies, Security Council seat, etc) and other former Soviet states either support the continuation or indifferent. Yugoslavia continuation is more contentious topic.
(The USSR dissolved before the world-wide-web was even a thing.)
If Barclays can get their own vanity TLD then Yugoslavia should be able too.