O que significa If the west is condemned as decadent, the strongmen do not see westerners waving placards calling for fewer freedoms. ?

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So, "strongmen" here refers to political leaders seen a dictators or authoritarian. The article gives examples of these kind of leaders (Putin, Xi, etc.). But despite these leaders criticism of Western democracies, the citizens actually living in these democratic countries still want to retain the freedoms and rights that they have. The "waving placards" statement is meant to be ironic or sarcastic. It refers to protests or demonstrations where people are usually demanding more freedoms, not less.
I think the author is trying to say that the more freedoms you give people, the more freedoms they will want (or at least this is what dictators believe)