I think I just stumbled across another error in the books. I think the Wastelander Featured Foe should have a Will rating of 15.
In the Foes section, the Wastelander has the Will Resistance called out as being level 10 (on page 197). This is 2 lower than the default Will 12 for all Featured Foes (per page 191).
However, for all the other Featured Foes who have an entry in the Resistances line of their stat block, the Resistance that's called out is boosted above the baseline for Featured Foes. The special Resistance that's called out is rated at a 10, 11 or 12. For Strength and Constitution, the default stat is a 7, so they are getting a bonus of +3 to +5 above the baseline. But for the Wastelander, a Will 10 is effectively a -2 penalty on Will.
Given that the description of Wastelanders says "Caked in the dust of the desolate future, this survivalist has survived better than most." Which makes them sound stubborn and determined, not weak-willed. So I'm guessing that when page 197 was written, page 191 had not yet been written. So they thought 10 was a +3 bump above the default starting value of 7.
It's an easy fix, just bump the Wastelander's Will Resistance up to a 15. This does put him at the same Will Resistance as a Boss, but I think that's likely the intended power-level for this one rarely-used stat.