I love the Yellow Submarine and I love the parallel of "losing color = death."
I'd like to see the police illustrated more like the Blue Meanies and their minions. I assume you're trying to villainize them? As-is they look like residents of Sgt. Pepper's... land... Whatever it's called.
Nice I wanna make them look like blue meanies but I'm afraid of crossing the line between parody and infringement. Yeah I never really thought through the colorless death part, I just want there to be a pile of stuff that the killdozer is pushing that doesnt destract from the other parts. Yeah Youtube killdozer and prepare to have your mind blown.
But I think you can have some creative licensing with a Blue Meanie-esque character without worrying about infringing.
Dealing with the concept, I'm not so sure referencing some flash-in-the-pan youTube video is really doing this idea justice. If you could make it a lot more culturally reflective in a general sense, the design would take off. I know that's a rough thing to do (abandon your original idea), but I really like the idea of parodying the Yellow Submarine using cops as Blue Meanies.
But yeah, it really comes down to doing what you want, so good luck!