Harry is an amnesiac cop who was a moralist before the amnesia. His moralism is also psychologically tied up with stuff like his ex-wife. It's what his brain defaults to when he considers questions of how society should operate and how to treat people. Kim's the same way. It's what Harry has been conditioned into, so his empathy is the same thing as his default political outlook.

Rhetoric is communist because Harry has to be talked into it. It doesn't quite appeal to his conditions or interests. His first step to becoming a communist is talking himself through it. He goes through a period of basically making stuff up in his head, or adopting a persona. Yeah, that's how I'd describe it. His communism is a persona he's trying to adopt, because he hasn't spent much time with actual communists or engaged with the literature.

Like there's a quote when Harry is talking to the deserter. "I'm a communist too. I have communist thoughts in my head." And that's all it's been for Harry at this point, it's a bunch of thoughts swirling in his head, changing his default outlook. To a good outlook I should say. The communist quest is the only one where he seems like a more optimistic person at the end. Harry's able to cope with pain in a more healthy way.

Also ultraliberalism's skill is Savoir faire because that entire ideology is about being a smarmy smug asshole.