Emergency Loads, Standby Generator, Two Services

Question for you all.

Background: An existing building has a standby generator (over-sized for its original intent with a lot of capacity available) to supply power to emergency loads. Client would like to add a second utility metered service on site (for com/security equipment) and use the existing generator for backup power on new service. Existing generator has a breaker/disconnect already on the enclosure, which then has typical configuration to an ATS, then to E panel, then to E loads. Emergency loads, existing and new, are all communication/security. No hospital type life safety loads picked up.

See photo for more information.
My question to you guys...
Per NFPA "
445.18 Disconnecting Means Required for Generators.

Generators shall be equipped with a disconnect(s), lockable in the open position by means of which the generator and all protective devices and control apparatus are able to be disconnected entirely from the circuits supplied by the generator except where the following conditions apply:

(1) Portable generators are cord- and plug-connected, or

(2) Both of the following conditions apply:

a. The driving means for the generator can be readily shut down, is rendered incapable of restarting, and is lockable in the OFF position in accordance with 110.25.

b. The generator is not arranged to operate in parallel with another generator or other source of voltage."

Would it be required to have (2) enclosed, lockable in open position, breakers near the generator. (1) 600A for existing service, and (1) 300A for new service (currently detailed in as black boxes near the gen for reference)? So essentially we would have a 600A internal breaker protecting the generator, and a disconnect serving each load down stream. Or is there another code compliant method that wouldnt require an additional 600A enclosed breaker.

Thanks in advance!