It doesn't even make sense. Hypersonic missiles are good at being hard to take down themselves. But you don't need that to take down an aircraft. You need super sensitive radar systems, since the claim is that these aircraft reflect about as much energy as a bumblebee would.
Do note that the this claim comes from the same people who don't hand out any actual specs and always fly with an additional reflector. The latter makes it easy for radars to see them again. This is helpful in allied airspace, but it also makes it impossible to verify the claim.
Also note that modern radars are sensitive to how fast an object approaches (or leaves) the radar. Bumblebees don't break the soundbarrier usually, so it is possible to see these planes, but you do have to tweak your radar for it. (Hence why the US doesn't give specs.)
I worked on the b-2 (has the same tech nearly). If you take a panel off to inspect anything or fix an issue the jet has to go to the paint shop to have the paint re-applied because its most of what makes it stealth. The paint absorbs radar.
The most bat shit insane part of this is the missile absolutely cannot maneuver to intercept at hyper sonic speeds unless it's a nuclear warhead. In which case, yes we know you can down a plane with a nuke.