Polluting: I LOLled. I don't think we can consider 4000 self contained sloc pollution in a 20 million sloc Linux kernel codebase. But you should ask the kernel guys that thought android binder should be merged in mainline kernel, maybe.
Btw it is not possible to pursue what you proposed since anbox binder/ashmem are only synced with latest ubuntu supported kernel and they don't even compile on recent kernels. Otherwise, one possibility is a Linux mainline patch to made these modules loadable, or maybe you could simple `rm /dev/binder /dev/ashmem` if you consider them harmful.