I'm not seeing how the GP's idea could be used by bad guys to block access to services - it'd be something you could add to your firewall, if you don't use this

I'm not seeing how the GP's idea could be used by bad guys to block access to services - it'd be something you could add to your firewall, if you don't use this service, to prevent it's use in gaining persistence. If the bad guys can modify your firewall config, you already have a problem.