If you were really obsessed with liberation of the proletariat as a class you too would try to oppose and resist racism, colonialism, imperialism, sexism, cissexism, heterosexism, ableism, anti-immigrant bigotry, etc. If you gave a fuck about the working class and not just maintaining a slightly higher (or much higher) social position than others you would find the way these things harm and oppress the proletariat, as a class and as individual human beings, totally fucking unacceptable.
It’s not “an injury to one is an injury to all, unless that one of us is Black or an immigrant in which case fuck them”.
While it’s absolutely important for theory to discuss and really address how things like these are foundational and necessary for the development of and function of capitalism (not just coincidental to it), even if you didn’t do that, if you were actually even remotely committed to supporting the working class, you wouldn’t be okay with racist violence against its Black members, exploitation of its immigrant members, extermination of its disabled members, etc.