As expected, Sim's popularity with the people gave rise to serious apprehension in the government, leading to his being arrested along with another prominent Chinese leader, Gu Hsing-kuang, under the Sedition Act. Their case ran for two years, during which time they had to frequently be heard in court. Eventually the Malaysian authorities, fearing a reversal in public opinion, dropped the case.
「救星」被捕果然，沈慕羽的群眾魅力引發大馬當局疑懼，他和另一位華人領袖顧興光以言論觸犯「煽動法」被捕，案件審理兩年，期間他必須定期至法庭接受審訊、出庭，最後政府還是畏於輿論而撤銷案件。