I think you might have misunderstood what he meant or he may have put it a confusing way. ARFF (and the airports)
is where things get complicated. At Newark ARFF is dual alerted. They receive a voice call over 121.8 (EWR Ground Primary) and P25 Trunked (TGID Unknown). They communicate with the EWR CPD on P25 Trunked, PA Airport Ops Cars on 453.650 and Av frequencies, but for operations they operate on EWR Ground enroute to the alert but on operate P25 and 134.05 (EWR Discrete) with the aircraft during the alert. ARFF apparatus are all equipped with a stack of comms gear that looks like a whacker shopping spree including ADS-B equipment.
EWR administrative ops and maintenance now operate pretty much 50/50 between P25 and UHF EWR1-EWR4, with 3 and 4 having rarely ever been used except during extreme storms with large snow team ops.
TEB ARFF, Maintenance, Ops, and Police all operate and have always on EWR's talkgroups and frequencies with the caveat of being able to also operate on South Bergen FMA to talk to Hasbrouck Heights as they're second due at the airport, but often also respond for an Alert 3 or higher since TEB only has R61 and R62 and normally only staffs one due to lack of incident volume and lower mean air traffic.
All of the above also applies to JFK and LGA, just on their own respective frequencies.
Bridge & Tunnel Agents still utilize the following, but primary are on P25:
View attachment 90969
453.400 is also the primary frequency for most NYSDOCCS facilities and buses. In what context was the traffic you heard?