I think Mali acts as sort of a buffer in case of a HRE attack (based on what i've done in SP before, so just speculating here) - get a neighbour AI vassalise to you to secure one flank while you go on a rampage on the other. In case of war, the vassal feels the brunt of the attack and buys a lot of time for reshuffling troops toward that front.
Of course, since Vassal States are disabled and Mali is human-controlled, Mali could backstab, but I think Mali's military is not a real threat to India, and they'd have more to lose by declaring war on India...
Of course, since Vassal States are disabled and Mali is human-controlled, Mali could backstab, but I think Mali's military is not a real threat to India, and they'd have more to lose by declaring war on India...