Writing off the surrender of mainlanders of all their rights to "effective propaganda" is undercutting the very real sense of grievance and fear/hatred of foreigners already present.
Mainlanders may not like it to hear it, and I'll even go as far as to say the best strategy for discussing politics with mainlanders is to not directly tell them this, but their political canon is anomalously full of holes that are exposed when explored in any significant depth (yes I've been through this process with mainlanders).