That’s definitely possible, I seem to remember that it consists of 24 steel slugs or something like that. While a dense warhead would mean that there’s little space to be gained by changing it, 70kg are 70kg and certainly represent plenty of opportunities for saving weight. Perhaps the margin gained by lightening it considerably (or getting rid of it altogether) on MSE would be big enough to allow for this mysterious reduction in overall missile weight in addition to compensating for the larger motor?