Jeffrey Lewis often has smart things to say, but sometimes his articles make no sense, at least from a technical, on their face, perspective. If nukes really do fly, whether they fly over Russia or not is totally irrelevant. At a minimum, given only a heading, Russia would see that only the far east could be conceivably attacked, which is not a threat to the Russian nation, or its nuclear deterrent, and would not be the action of a power trying to attack Russia. In reality, satellites and radars would also be able to measure velocity, and this, even only with satellite and without radar, would make it clear that the target was NK. Russia might lodge a protest about its airspace being violated, but this would be comically minor compared to the rest of the diplomatic issues to be resolved after an actual nuclear attack.