Slightly speculative indeed
Is it even possible for it to burn out completely? ISON passed, or rather it tried, the sun's surface about twice the radius of the sun itself, and even then we had hopes that it could survive. 67p/Spiff-Zogwarg will be at 1.3 AU at its closest. That is one hundred times further out, which if my basic knowledge of astrophysics is correct, means around one ten thousandth of the radiation.
Regardless, I am quite exited over this. They are going to harpoon a comet. Apart from the Apollo 12 rum incident, how often are harpoons launched in space?