That mechanic did you no favors and if he's typical of most guys who do alignments, he doesn't really understand everything about what he's doing. Your Rubicon's caster is not adjustable the way Jeep built it at the factory. It only becomes adjustable when aftermarket cam bolts are installed on the lower control arm mounting brackets or if aftermarket adjustable length control arms are installed.
That said, I really doubt your caster angle is off enough to worry about it... the caster angle is not critical and as long as your steering wheel returns to center after you complete a turn, it's fine.
And the factory caster angle is only proper for an unlifted Jeep with stock size tires. With your larger tires and lift, your caster angle should NOT be the factory 7 degree optimal setting. You actually want less than that for 33" tires with 5-6 degrees of caster angle being optimal... not the 7 degree caster angle setting which is only correct for stock size tires.
The bottom line is I really doubt your caster angle needs adjustment unless someone installed cam bolts or aftermarket control arms and totally jacked it up... which I doubt happened.
The ONLY thing your Jeep has alignment-wise that needs adjustment after any type of front-end or suspension lift height work is done is your toe-in. And you can literally, without exaggeration, perform your own toe-in check and adjustment at home and set your own toe-in every bit (literally) as accurate as an alignment rack can do. Really.
Set your toe-in to between 1/16" and 1/8" per the instructions in this link... Basic Jeep Front End Alignment
All you need are a couple wrenches, a tape measure, some big water-pump pliers to rotate the tie-rod to adjust the toe-in and that's it. If the tie rod won't turn after you loosen both its clamps, odds are its threads are just dirty/corroded. Soak the threads with something like Liquid Wrench, PB-Blaster, Break-Free, etc. but don't waste your time using WD-40 which won't do it. If it's still tight, a pipe wrench on the tie rod will do the trick.