I really don’t think dual use is in any way worrisome if humanity has several institutions capable of asteroid deflection, and a tiny one if there is only one. Quoting a comment I gave to finm in his post on asteroid risks:
I don’t think the dual-use should worry us much. I cannot estimate how much harder it is in general to divert an asteroid toward Earth than away from it, but I can confidently say that it is several orders of magnitude higher than 10x [figure finm gives as example in his text] (the precision needed would be staggering). In addition, to divert an asteroid toward Earth, one needs an asteroid. The closer the better. The fact that the risk of a big-enough asteroid hitting the Earth is so low indicates that there are not too many candidates. This factor has to be taken into account as well.
But, even if diverting an asteroid towards the Earth would be only 10 times harder than diverting it from the Earth, dual-use does not need to be a big concern. To actually manage to divert an asteroid towards the Earth one does not only need to divert it, one also needs to prevent the rest of humanity from diverting it away on time, which is much easier. So, as long as a small bunch of independent institutions are able and ready to divert asteroids, dual-use does not seem a concern to me.
I really don’t think dual use is in any way worrisome if humanity has several institutions capable of asteroid deflection, and a tiny one if there is only one. Quoting a comment I gave to finm in his post on asteroid risks: