This is not a critical support or 702 install. Residential application.
Which is it? You stated
Customer has multiple servers (20-25) with UPS back-ups thus the larger generator to make up for the UPS loads.
Sounds commercial to me. As far as the NEC Art.702 is for optional standby systems. That Art. can and dose apply to residential,commercial and industrial. So if it has not been deemed as emergency or legally required by the AHJ it is optional.