The only reason hong kong is allowed the protests is because china doesn't yet have a full administrative presence there. The protesters know they won't be able to protest if china is in full control.
They obviously wouldn't want to be in the position Muslim Uighyurs or Falun Gong members are in. The CCP has killed at least 2000 Falun Gong members and an unknown number of Muslims and Gong members for organ harvesting.