I have never understood the big deal about organ donation. The dead person no longer uses the liver or whatnot and has no opinion. The other 98% of the body will be discarded anyway so why not recycle?
Now, whether it is better for many innocent people to die so that a terrorist doesn't live is up to you. You asked for a reason, not a good one.
It certainly isn't one in ten million "evil" doctors. Consider that you might be underestimating the likelihood because you want people to be organ donors. I'd say the main reason the official respectable stance is that you'll never have your organs harvested when you would live is that people want more organ donors so they fall for whatever belief helps make it happen.
I certainly couldn't care less what people might do with my body once I'm dead. Burn it, bury it, ignore it, worship it -- whatever floats their boat.