I think you misunderstand the origins and meaning of the saying. The saying itself is based on historical context, where liberals in places like Italy and Germany chose to support growing fascist movements in the name of maintaining some sort of stability and perceived normalcy, instead of combatting those movements alongside communists and socialists. As an example, in my opinion we are seeing the same history play out again in the modern United States as various corporations, universities, and state governments, etc are following along with certain policies of the Trump administration in order to maintain normalcy instead of choosing to resist those policies and cause an upset. The saying “scratch a liberal and a fascist bleeds” is based on the historical kowtowing of moderates and liberals to fascist movements instead of choosing to resist.