I've not seen anything mentioned of the balancing factor of needing to succeed at a Discipline check to move objects to attack things with the proverbial AT-AT. Even if you interpret the RAW to mean that +1 FP spent jumps you up to silhouette equal to number of Strength upgrades (which I really do think that's the way it is written), you must still succeed at that check to do any good with it. You must roll enough successes and enough FP. That's not as easy as it sounds.
So, if you maxed out on Strength and Range upgrades, and jumped up to a FR of 2 (which, assuming your player is a complete cheeseball and took the shortest route possible to intentionally annoy everyone around him, would require at least 200 XP)...
1 FP to activate Move
+1 FP to jump up to Silhouette 4
+1 FP to Increase the range.
Note that this does not include the XP cost and odds of also succeeding at a Daunting (4) Discipline check.
I just did 10 test rolls with a FR 2 and a Discipline skill of 2 ability + 2 proficiency. Out of those 10 rolls I only came up with one that produced even one success and enough LS points to fuel the power. Two other rolls produced one success and enough DS points to fuel the power.
I dunno... this sounds like a high XP investment for a relatively low success rate. Who is going to want to take a chance of 1 in 10 while an AT-AT is plodding towards them?
I should also note that f you're not the type of GM who would use the tools at your disposal (allowing them to use DS points without fear), you're missing out on the inherent concepts that balance the powers. Not to mention the fact that if someone does something as flamboyant as throwing an AT-AT at someone they will likely have the entire might of the ISB hunting them down. A considerable portion of the Empire's resources is being devoted to finding characters that can do that sort of thing and wiping them from existence. If you're not factoring in such story-based elements, you're not factoring in the assumed balancing factors of the game. That's not a power that is OP. That is a user that is ignoring vital aspects.
Now, as for simply pushing over an AT-AT... well, same argument above... the Empire would take notice. Aside from that, look at it from a "so what?" perspective. So he can knock over an AT-AT. So what? Looks great and scary, but when you boil it down to what has actually been accomplished... he took out one enemy. If your encounter is derailed by the loss of a single AT-AT... Don't rely so much on brute strength to make your encounters interesting.
Perhaps from a mechanical standpoint Move can be a bit overpowered. But there are a lot of ways to balance it out in session.