I think the argument is that for the previous 100 years, Imperial Britain had deliberately encouraged violent divisions between the Hindu and Muslim populations as a means of exerting external control, again this is called a 'divide and conquer' policy.
Your argument is sort of like saying, just because the British gave them the dynamite, they're not responsible for lighting the fuse.
Indeed, safe handling of dynamite involves not lighting the fuze deliberately.
What happened after the abolition of British Raj was in part a consequence of it, but I would not deny agency of the participants of the warfare that ensued.
Your argument is sort of like saying, just because the British gave them the dynamite, they're not responsible for lighting the fuse.