I disagree, this is just obstructionism and jockeying for negotiating position by the Russians. A hyperfast weapon might be strategically destabilzing, but only if launched in great numbers at multiple strategic targets. In fact, the same could be said of a conventional ICBM, or even subsonic aircraft, manned or unmanned. In the event of a limited accidental launch, or an unauthorized attack by a rogue commander, the target state could afford to absorb the strike, evaluate the motive of the attacker, and then decide whether or not to retaliate.

Destabilizing weapons are those that threaten to take out, or seriously degrade, a nation's retaliatory capacity. This puts the target state in a position of "use-it-or-lose-it": a hair trigger scenario that could easily spiral out of control and provoke a full-scale nuclear exchange. Personally, I think this is a great tactical terrorist-buster that poses little or no strategic threat to any organized state (especially if accompanied by a hotline call to concerned treaty states prior to use). ("Yo, Ivan, we just launched three conventionally armed hyperfasts at 2300 UT at unspecified targets in the Mid-East from platforms in the Persian Gulf). The Russians would know this could not be a precursor to a strategic first strike against their territory, but they would have no way of warning any of their pals who might be on the target list, either. It is the latter possibility that the Russians are probably most upset about.

They would have legitimate gripes about some other options, though, like orbitally launched weapons. They would have no way of knowing how many warheads would be stationed on an orbiting battle station, and would have almost no warning time to evaluate and respond if it launched them. And of course, if we were developing the capability to deploy large numbers of these hyperfasts, within range of the Russian Federation, then they would certainly have every right to be concerned.