Yes, front shaft spins anytime vehicle is in motion - note the lack of lock-out hubs on the front end as on older Jeeps with traditional hub/bearing assemblies instead of the unit bearing hubs on the Wranglers.
The squeaking could easily be u-joints or the centering ball in the double-cardan end of the shaft, which is notorious for going dry when not properly maintained. When was the last time you had the shaft off and replaced/lubed the u-joints? The OEM joints are sealed, so you'd have to actually pull them apart to lube. Replacements can be either way; I prefer the greasable Spicer joints, but some folks prefer the Spicer sealed units. Whatever you do, don't put cheap-o u-joints in, it is false economy in every sense of the term.
If I were aiming to diagnose, I'd pull the shaft and re-test. If you still have a squeak, you know it isn't the shaft AND you can re-grease/rebuild the shaft while it is out (it probably needs it anyway, right?). If the noise stops, well, you have your answer and should rebuild the shaft.