They were not actively silenced, they were used to grow and control opposition groups and promote the narrative that covid is real. The scientists that rightfully claimed that there is no proper evidence for the virus to exist in the first place were the ones who actually were and still are silenced. People like Stefan Lanka, Andrew Kaufman, Tom Cowan and others were lied about, their scientific careers were destroyed and all the funding was pulled from them. One russian scientist was actually murdered a few days after he told everyone the truth about virus not being real at russian analogous meetup, such as "Barrington Declaration".