> Current costs to launch a kg to orbit are something like $2,000-$6,000.

This is false. Launch on Falcon 9 is under $1K/kg.

Moreover, current launch costs are just a milestone toward future launch costs, which promise to me much lower. Ultimately launch will be a few times the cost of propellant (just like air travel), so $10/kg is a reasonable expectation.

> vaporizing in the atmosphere

How does this happen? Launch explosion? That doesn't vaporize an armored container. Entry from near-orbital speed? Also survivable passively.

The result of an accident will be tracking down the armored canister(s), cleaning up any local impact fragments, and prepared the stuff for another launch.

The armored canister doesn't have to be sent beyond LEO, so it could be reused, and doesn't impose a mass penalty on that beyond-LEO transport system.