That sounds entirely too complex of a plan considering the creature's goals. I would think that a tactical strike would work better then long term diseases. As for getting rid of a disease, the best way would be to first get rid of the largest cell cluster and then treat the rest with its killer. That was probably why it took so long.

I can understand your mistrust given what I am hearing, but I shall warn you not to get him riled up - I do not enjoy stabbing other pieces of myself even if they do deserve it.