Admittedly, improving the [Blood Shield] could work against Khan's precautions. Pushing the defensive alien technique to his new physical limits could make him able to endure pretty much anything, increasing his survival chances if he forced his organization to take him down.
However, the issue had another side that could work in Khan and his forces' favor. The [Blood Shield]'s drawbacks had always been harsh, and their intensity grew with each superior checkpoint. Khan might end up abusing it if he lost his sense of self, killing himself in the process.
Moreover, Khan needed familiar sensations to remain grounded in reality, and few of his techniques had accompanied him for so long. Chances were the eventual heaviness on his chest would help him fend off the invasive memories, saving his forces from his terrifying outburst.
