Put simply, the speed of the ground being shoved out of the projectile's way is equal to the speed of the projectile, and it cancels out.
I did take the link and read most of the article, but this wasn't obvious to me.

The US space program exists and our military has private access to it. I think it's a bit naive to assume that they wouldn't be weaponizing space to some degree.
Oh I totally expect them to weapnise space, it's just a question of to what degree we can do so at this moment in time.

They also have a vested interest in making boatloads of money and if they have the money and power to suppress some tech, they have the money and power to own that tech and profit off of it.
I'm really trying to avoid getting too deep into this subject in this thread. It's not physics, it's conspiracy. What I will say is that the next generation of energy should, in theory, be abundant. Oil is scarce. Therefore, oil will be more expensive (and thus higher profit margin), than any theoretical newgen energy. An energy company can sell solar panels, but it can't sell sunlight.