@PretzleMe
two things, the assumption that bases elsewhere wouldn't pick up the slack, or that additional bases would not be constructed or converted. in my opinion destroying the base wouldn't have spared more people form exaltation, might have even sped it up.
and second, under my original assumption above, you'd be spending more angaran lives for basically nothing. or at best a short reprieve.
but, that's just how i see the situation.
---edit
i guess i should also note that we're never told if there are more than one single exaltation facility, i think logically if exaltation is so vital to the kett's existence, and they've got the capacity to create enough kett to keep the war-effort moving, there has to much more then just that one, there have to be several, i'd even bet there's several such facilities on voeld itself. though i've got no proof, just logic, common sense, and my eyes.
---edit again
if you're asking why the kett cardinal was pleading so seriously, and willing to make a bargain? it's simple psychology. to me it seems the facility is like some kind of religious temple, as well as an exaltation compound. she's pleading because the structure itself has religious significance. like a mosque, church, or a cathedral.