Based on that, if earth intersecting in less than 1 orbit is prohibited, ALL ICBM's are prohibited. I'd like to see the original treaty language, because I bet it doesn't ban what that interpretation says.
It is very difficult to achieve treaty language that bans less than one orbit without banning normal ICBM's, as any large ICBM is quite capable of (with a reduced payload) achieving a long way trajectory.
And that is mathematically provable.
What I would bet is that the treaty banned missiles with a payload capable of operating for greater than one orbit--basically, banning PBV capability >90min (or some period of time)