its 27-tonne weight could be launched to LEO by a single Delta-IV Heavy and hauled off to intercept by a second launch vehicle.
I find this an interesting statement. Running the numbers, I find that you'd have to be using a rocket burning something rather better than H2/O2 (we're talking Isp >500 just to reach escape speed, much less to reach the target rock) to allow two launches of a delta-IV heavy.
And this entirely ignores that noone actually has a Tsar Bomba sized nuke available to be detonated.
Oh, and you didn't allow for a backup - if your delta-IV heavy blows up on launch (no it won't be a nuclear explosion, much less a tsar bomba sized nuclear explosion), getting another Tsar Bomba put together with a launch vehicle in your now shorter window (and it'll require more deltaV, since you'd presumably do your first launch attempt at the point that minimizes deltaV requirements)...
In other words, it'll be a bit more difficult than two delta-IV heavy launches, even if things go perfectly. If they don't it'll be a lot more than two...