Once again, you need to "pay attention to detail." Or, as Rush point out, "words mean things."
210.52(D) is where we get the requirement for bathroom receptacles. That section says nothing about "residential," but does start out "In
dwelling units ..."
There is no intent for this building to be a dwelling unit, nor does it contain other features -such as a kitchen- that would be consistant with such use. That the property is zoned residential, or that there is a dwelling unit associated with this shop, matters not at all. As such, there is no requirement for any receptacle in the bathroom -even if there is a sink- or a dedicated circuit. All the guy wants is a toilet. Elsewhere, there's likely a sink for clean-up, but, again, we have no reason to believe that the sink is in any way associated with the toilet.
If we do decide that this is a dwelling, the bathroom circuit is the least of our worries. Heating system, smoke alarms, laundry circuit, AFCI's, receptacle spacing, minimum service size, ... all manner of things become required.
I must admit that, over the years, I've done all manner of things in my garage. Reaching for the curling iron isn't on that list, though.
