Plain and simple your electrician didn’t look at the code changes for NEC 2020 edition from the previous 2017 edition.
The Emergency Disconnect is for the fireman’s safety when entering a house if there is a fire.
As for there still being live power at the meter that is not a safety issue for the fireman. If the fire has burned over and or around the meter socket the Utility Power Co is called and the power is disconnected from the dwelling unit.
Power Companies do not allow a disconnect ahead of the meter socket for a residential dwelling unit. Sequence is meter >> Switch >> Fuse.
As for securing the EM disconnect on the outside of the house there is a provision on the enclosure for installing a Padlock that secures the outer metal cover. The Fireman has a master key for all Padlocks made... It called a bolt cutter.
The AHJ (Authority Having Jurisdiction) has the final say. If the electrician is arguing with the inspector he is only digging the hole deeper. I hope you got a contract price from the electrician for doing the job...