Would bottle Conditioning instead of kegging fix it some i wonder?
I've had enough bottle-conditioned, diacetyl-ridden homebrews to say 'probably not', but I'd be interested to know if yeast releases/takes up diacetyl during bottle conditioning.
I wouldn't be too motivated to bottle a beer with high diacetyl. If I can't fix it beforehand, I'm not wasting the bottles/keg/fridge space.
If rousing doesn't work, you could make a small starter and pitch it at high krausen, or krausen w/ another fermenting beer.