The usual catch-all for things they don’t like is/was “picking quarrels and provoking trouble”. I don’t think there are specific offences and penalties specified https://www.chinalawtranslate.com/en/2015nsl/
Plus what you are referring to seems to be what some of the 12 are alleged to have done? Still not NSL-worthy even by HK standards, but that’s for HK courts to decide.