Might be a requirement in the mechanical code or some other code. Had a fire inspector ask for a disconnect on a boiler with a red cover even though the boiler was 5' away from the circuit breaker in the service.
I just did a project where we installed new boilers in a couple school buildings. I think the "Emergency Power Off" requirement is triggered once the BTU capacity of the boiler reaches a certain level. On this project they wanted "EPO" switches near the entrances to the room. If the room had more than one entrance then there needed to be a switch near each entrance. These were not "disconnect" switches for the purpose of servicing, LOTO, etc, but "Emergency Power Off switches. I also have an industrial customer with a process steam boiler that a few years ago we had to put similar switches at entrances. We have seen the combustion area doors blown open before on this install, you do not want to have to enter that room to hit an EPO under those conditions, the EPO's on that install are outside the boiler room right next to the entrances. 125 PSI steam inside at least a 10,000 gallon vessel (not sure just what the capacity is but it is a huge vessel) is nothing you want to be close to if something ruptures, and the BTU output of the burner is nothing to disregard either should something go wrong with it.
This has been discussed & cussed adinfitium. One method used here is a handy box with a single receptacle for the line side. For the load use a 3 ft pigtail. During a power outage you can plug the pigtail into an extension cord from a generator. This has satisfied the AHJ for means of disconnect.
I guess if AHJ wants to accept that, then so be it. There is such a thing as small transfer switches that would be NEC compliant.