Sure, the threat of using "Emergency Regulations Ordinance" seems credible. Though that makes one ask of all the hypothetical outcomes which according to
https://www.elegislation.gov.hk/hk/cap241 includes "arrest, detention, exclusion and deportation;", "authorizing the entry and search of premises;" etc, why is selective internet blocking the one that gets a pre-emptive denouncement rather than say randomly getting snatched at home by the police?