The point is, you should never find yourself in a state where you have enough excess income after your malaria prevention donations but won't sign up for cryonics because malaria prevention is more important to you.

EDIT: The real point is more that comparing with malaria prevention could be a dodge-- you can make any purchase you want look bad via that comparison, so you need to do it consistently or you're using it to selectively denigrate some ways of spending money.