That is a great analogy-and actually the same logic holds. Just because there is black on black crime, does not mean that white supremacy doesn’t exist and hasn’t damaged that black citizenry extensively, and in the case of Black Americans, white supremacy is actually the cause behind black on black dysfunction; and while American foreign policy can’t be blamed for causing Islamic dysfunction, it certainly exacerbates it.
It is illogical to say, blacks or Muslims are violent with each other, and therefore no outside force has any relevance or impact. Of course it does. If a bomb goes off in a dysfunctional community, that will make the dysfunction so much worse; and also provides a common enemy who is deeply, deeply despised by everyone in the community.