yeah and considering that their libraians (if they had any) couldnt influence their minds due to their chakra, instead of drawing from the warp safely they make their own power source, however both are about equal in limiations, but chakra depletion or overdose just goes to death, to much drawing from the wwarp turns you into a deamons play thing, even though i dont think the warp would be anywhere near their planet, since natural chakra is pyshcial power, so i would guess it would just balance out any sort of disturbence or tears in the warp easily. Also consider demon hosts...the bijuu would be highly offended that the deamons would try to escpae into their world...which THEY rule, so i would guess that chaos itself fears that planet and stays the hell away, at least untill it has the entire universe in its grip.
Also i would say the sage putting jyuubi into the moon had the effexct of making a "black spot" in the warp, or a blind spot, so the imperium couldnt get any sort of reinforcement for centuries...even if they did commit an extermamartus, they wouldnt have a damn planet to live on, only their slowly degrading ships...even then the regular crew would die and the space marines know jack shit on piolting an entire ship without navigators or servitors....(most of them anyway)