As long as you are not disturbing the members of public nor giving speech. Anyone can gather at a food court such as that Bugis Street FC. Order your food / drink and talk to each other, shake hands, take photos etc. Tell the mata not to exceed their powers provided by law. If the NSP wished to cater say 20 tables and thank their supporters, no law can prevent that. Record what the conversation with the mata and post on youtube.
Incompetent Mata damn coward wanting to make their own job super easy at the expense of the citizens, and they actually knows little about law, that is something I had repeatedly proved in court.