I think it's a scare tactic. The lockout will get publicity and then people will be less confident about coming to future rallies.
Source: wiktionary
Scare tactic
Synonyms for "scare tactic" (6 found)
Ranked by relevance and common usage.
Sample sentences
2 total sentences available.
Invoking cancer is a scare tactic, not a health education strategy. The juxtaposition in the various iterations of Gardasil advertisements of the word “cancer” and the message “you can do something” put parents in a blameworthy position. The current advertisements for Gardasil 9 hardly mention the vaccine. Instead, in these ads children blame their parents for their failure to protect them from a potentially fatal illness.
Source: wiktionary