> I agree on this point. But since the proposal is for a generic design to deal with any incoming impactor, be it comet, asteroid, or even generation ship, then a design that can handle any impactor without modification is needed. There won't be time to design a modification if it is actually needed.
And this is where I would say _what!!???_ at lest if we were in person. "Any incoming impactor" includes objects of such potentially high kinetic energy, and of such unlikeliness, that we cannot even include it in any practical discussion. That includes, for example, intrastellar planetary bodies, "rogue planets". And that is where such a discussion would need need to assess, right from the start, trade-offs of likelihood of combinations of mass, velocity, and lead time to deal with it.
This was played out in the Rosetta Comet mission, which did _not_ succeed in embedding anchors in the cometary surface. Expecting a single design to handle both intra-solar-system objects, such as those from the Astroid Belt and of much smaller relative velocity to the Earth, and a cometary body that could be expected to be far, far colder and of a much larger relative velocity.
So right there, in the necessary requirements, are two profoundly distinct missions that might require two very distinct designs. Let's not limit such a discussion from the start in a single idea or technology that _must_ handle both.