Oh boy, theory fighting at its finest.
First off, Scorpion is not keeping out anyone with a grab. He has NO footsie tools to supplement it. A character like Sektor or Ermac can get away with dash up grab because they have specials that can commit your opponent to blocking on approach, but Scorpion really has no safe way of doing this to you. At best, he has D4 takedown and F4 takedown, both of which leave him right up in your face at -4, where you have to respect a poke followup. Committing to that basically sets yourself up for an attack and grab mixup. Suffice to say, neither of these is a compelling poke tool.
Better yet, air throw? Why is Scorpion trying to "keep the opponent away" with his air throw? Either you're suggesting that you should AA with it, or that you should just jump at your opponent in an attempt to air throw them, neither of which is even remotely sensible. Scorpion's best AA options are standing 1, D1 and B2. If he absolutely needs the consistency, he can just uppercut. There is no reason to be using his air throw outside of combos, or jumpkick air throw.
Here's a great one: His D4. What are you going to accomplish by playing keepaway with this? It's ZERO on hit. Scorpion mains constantly complain about this, and I can't blame them. It has decent speed and great reach, but he's not establishing anything with a D4. At best, he's just momentarily stalling his opponent or interrupting one action, but no one save for Mileena and Sonya can use their D4s as a significant footsie tool. Those characters have D4s with decent hit advantage, and much more generous hitboxes. EX teleport doesn't make a whole lot of sense, either. Unless you really cannot afford to eat a hellfire, there is just NO reason to jump against Scorpion from that distance.
Bottom line: NONE of this works. I can't think of a single decent character this would even be effective against. Rushdown characters like Cage, Sonya and Liu Kang give him trouble. Zoners like Kabal, Kitana, Kenshi, Cyrax, Mileena, Reptile and Sektor can beat Scorpion by rushing him down. I wouldn't even be surprised if Freddy could. In fact, name me more than three or four characters this can be effective against, with your arguments for each. I can't see this working on anyone outside the bottom tier, in which case it isn't effective because it's a sound strategy; it's effective because your opponent's character just isn't good enough to exploit the holes in it.
