As an electrician, and my understanding of the NEC that I was taught in my apprenticeship is that you only have to bring wiring up to code if you alter the existing wiring in some way. Or I guess if you alter the framing, e.g. adding walls.
Cabinets have nothing to do with electrical wiring unless you cover something up, add an outlet, or move an appliance. If you don't do any of those things, nothing has to be brought up to code. The second you add an outlet or move an appliance, the wiring in the whole kitchen needs to be brought up to code.
I love homeowners who buy an old house, and then get mad that everything wasn't renovated to their satisfaction. They own that house now, it's their project.