The best I can tell based on the first post, the JHA quoted 230.2 for his/her ruling. Although there are two buildings, only one service is feeding both of them. Therefore in order to disconnect the power of the service, when multiple disconnects are connected to one service, they must be grouped together per NEC. Local code and site conditions define the word "grouped" and location(s) of the disconnects.
Another way to look at it is from a fire departments perspective. They arrive on the scene and the house is on fire. To locate the power, they are taught to look for the meter. They locate the meter and see it on the garage. They go inside and locate the main for the garage and shut it off assuming the power is off to the house. They are not going to read the panel legends or look for placards to go on a hunt for a second disconnect. They are focused of the fire and getting anyone inside out ASAP.
Meter pulling is only a last resort. Doing it wrong can kill the person popping the meter. If the disconnects are grouped together, they arrive and shut them all off. Whip, bam, boom, move on to the fire.
