Sorry, the quotes got all messed up.
I'm not sure what you mean here. Force rating 1. Has Move Basic Power. Requires one Light pip. Has Strength upgrade four. To lift a silhouette 4 will only take one more light pip. I don't see how that is not in line with the CRB. Now last adventure he did pull a gun using move, and he should not have, as he did not have that upgrade yet, but he does now. With that upgrade and two Range upgrades, he can pull a blaster from someone from long range on two light pips. At short range he can hurl a silhouette 4 into someone doing 40 points of damage will take two force pips, and a Discipline Check (1Y, 1G) vs ranged defense.
He does not have the 4 Strength upgrades yet, only 1, but still it doesn't matter if it is one or four upgrades.
I fail to see how Force rating 1 is limited. Yes, most things require 2 light pips, 3 in 12 chance. Not great, but doable.
He has a 3 in 12 chance to knock over an AT-AT at short range. I don't really see that as limiting.
I think a player with a single Force die is limited. I'll explain:
30 Base
10 Upgrade Strength
5 Upgrade Range
5 Control
That's 50 XP to be able to move a Silhouette 1 object at Short range and throw it for 10 damage. With only a 25% success rate if he doesn't use dark side pips. The odds go up to 33% (I think?) when using dark side pips too. Still not great, and comes at whatever cost you as a GM deem appropriate.
And then there's the Discipline check. I didn't count the XP you'd put into Discipline, but at that point it's not a big check so it's probably not a big deal.
For some perspective: That same investment of 50XP for a bounty hunter could get the first four ranks of Ranged Heavy; making him a pretty good shot. He's succeeding regularly at that point and can probably do so up to Long range. I don't want to bother with all the possibilities about characteristics, weapons, attachments, mods, etc. Point here is that non-force users investing this amount of XP into a single skill can potentially deal more damage and do so more consistantly than a FSE with Move. That's what I mean by limited. A Force-user can kick some ass, but any character who invests in a single thing will be able to kick ass at that thing. The difference I see as limiting is that the FSE will succeed less often.
Now here's another thought:
Your player is holding people up and turning them around to not face the party? To me that is fine manipulation and should required that 15XP upgrade at the bottom of the tree. It also is going to require an increasingly difficult Discipline check each round to hold the NPC up. Maybe the NPC makes an opposed check too.