[stcredzero]

the part about the difficulties notes that it holds nuke-scale energies

Nuke scale energies get dissipated in the atmosphere on a regular basis by thunderstorms. I suspect it may be possible to ensure that most of the mass burns up in the atmosphere and is dispersed.

That would exclude the downtown-to-downtown feature.

A rocketplane could "rendevous" with the electromagnetic loop at high altitude and then be accelerated and decelerated for the bulk of the cross-ocean trip, then land at an airport.