I understand the idea that "Hard boiled cop and dolphin" came in a bad timing, i also believe that the work in a very convoluted moment. Wherever i don't think that this is gonna have a huge impact in how the public interact with it, mainly in countries were the protests are not so prominent. For example, in my country Brazil, we're have some protests that against police brutality, those influenced by the american protests, wherever, some weeks later people changed their focus, instead of police brutality, people start to go against the government, who's doing a terrible job at managing the covid crisis. Is possible that the same thing happened at Japan, the frustration and focus, went to something that the people perceive to be more present in their day to day lives. Other point, is that even though people are frustrated with irl cops, it is possible that this frustration does not affect the way people perceive fictional cops, just look at Brooklyn 99, at least in my country, it still being treated as a great series, and no one seems to have changed their perception of the characters because of the present moment.
Besides i don't think the manga shows hard boiled cops as a good thing, even though they have a cool moment in the final part of the chapter, the rest of the story focus on how goofy and silly Boyle ideas are, he though boxes being stained with nosebleed, instead of cool fighting blood, as example. Wherever i agree, that some moments during the car scene, can be perceived a bad taste jokes.
In relation with the boob humor, i think it fits the idea of story. He's not a super cool guy, who is cold as steel, he's just a normal guy, who consumes too much hard boiled media. He having nosebleeds, shows how silly he really is
(And just to clarify, i'm not saying that policy brutality, is something exclusive of the US or that it's a lesser problem. It's just that countries have different views and problems. And what people perceive to be their biggest source of concern in the moment, change from country to country)